Angels can be present in vast numbers and yet remain unseen

2 Kings 6:15-17

When the servant of the man of God got up and went out early the next morning, an army with horses and chariots had surrounded the city. "Oh no, my lord! What shall we do?" the servant asked. "Don't be afraid," the prophet answered. "Those who are with us are more than those who are with them." And Elisha prayed, "Open his eyes, LORD, so that he may see." Then the LORD opened the servant's eyes, and he looked and saw the hills full of horses and chariots of fire all around Elisha.

The horses adn chariots of fire mentioned here are learly heavenly creautres. Elish couls see them but his servant could not until his eyes were open. Fire speaks of the presence of God adn the the horses and chariots are the appropriate counterpart to a hostile Aramean army. No doubt the norm is for us not to see the angels. There is no obvious need for our eyes to be opened to the presence as Scripture confirms the fact again and again.

Angels are involved in miracles, live in heaven and have a measure of greatness

Psalm 78:25 Human beings ate the bread of angels;* he sent them all the food they could eat.

We know that there was something supernatural about the manna that the Children of Israel ate in the wilderness. It fell daily from heaven just where the people were. It had variable properties that made it rot if kept overnight except on the night before the Sabbath. Asaph here calls it the bread of angels. Now why does he call it that? Certainly, angels are spiritual beings and have no need of food. The Puritan Arthur Jackson makes three suggestions as to what Asaph may have in mind

1. Because it was provided and sent by the ministry of angels
2. Because it seemed to come down from heaven, the dwelling place of the angels
3. To set forth the excellency of this bread, that it was meat, as one would say, fit for angels, if angels needed meat.

Coming at the matter from the other end then, we remind ourselves that God delights to do his miracles through the agency of angels and that heaven is their home, there in the presence of God. They are also a useful benchmark for excellence or greatness.

* The Hebrew has mighty ones but the LXX legitimately has angels

Angels were involved in the giving of the law

Acts 7:53 you who have received the law that was given through angels but have not obeyed it.

Galatians 3:19 Why, then, was the law given at all? It was added because of transgressions until the Seed to whom the promise referred had come. The law was given through angels and entrusted to a mediator.

Hebrews 2:2 For since the message spoken through angels was binding, and every violation and disobedience received its just punishment, ...

Deuteronomy 33:2 He said: "The LORD came from Sinai and dawned over them from Seir; he shone forth from Mount Paran. He came with myriads of holy ones from the south, from his mountain slopes.
Psalm 68:17 The chariots of God are tens of thousands and thousands of thousands; the Lord has come from Sinai into his sanctuary.

Matthew Henry comments on Acts 7:53 that the law is said to be received by the disposition of angels, because angels were employed in the solemnity of giving the law, in the thunderings and lightnings, and the sound of the trumpet. It is said to be ordained by angels (Gal. 3:19 ), God is said to come with ten thousand of his saints to give the law (Deu. 33:2 ), and it was a word spoken by angels, Heb. 2:2 . This put an honour both upon the law and the Lawgiver, and should increase our veneration for both. But those that thus received the law yet kept it not, but by making the golden calf broke it immediately in a capital instance.

Barnes notes that the phrase given through angels has been supposed to mean that the Law was given “amidst” the various ranks of angels, being present to witness its promulgation. Others suppose that the angels were employed as agents or instruments to communicate the Law. All that the expression fairly implies is that the Law was given amidst the attending ranks of angels, as if they were summoned to witness the pomp and ceremony of giving “law” to an entire people, and through them to an entire world. It should be added, moreover, that the Jews applied the word “angels” to any messengers of God; to fire, and tempest, and wind, etc. And all that Stephen means here may be to express the common Jewish opinion that God was attended on this occasion by the heavenly hosts, and by the symbols of his presence, fire, and smoke, and tempest.

Angels can destroy people

1 Chronicles 21:15 And God sent an angel to destroy Jerusalem. But as the angel was doing so, the LORD saw it and relented concerning the disaster and said to the angel who was destroying the people, "Enough! Withdraw your hand." The angel of the LORD was then standing at the threshing floor of Araunah the Jebusite

1 Corinthians 10:10 And do not grumble, as some of them did - and were killed by the destroying angel.

Exodus 12:23c and he will not permit the destroyer to enter your houses and strike you down.

Acts 12:23 Immediately, because Herod did not give praise to God, an angel of the Lord struck him down, and he was eaten by worms and died. 

More than once we hear of angels involved in the act of destroying people, killing them. It is not entirely clear whether such angels may be fallen or unfallen. This appears to be what happened in David's time, although given the reference to the angel of the LORD, it may be God himself who is in mind. Paul suggests in the New Testament that a destroying angel was responsible for putting people to death in the wilderness. The destroyer of Exodus 12 is popularly thought of as the angel of death and this may be the reference here too. In Acts Herod is killed by an angel who inflicts a terrible disease on him.

Angels are always in God's immediate presence

Luke 12 8, 9 I tell you, whoever publicly acknowledges me before others, the Son of Man will also acknowledge before the angels of God. But whoever disowns me before others will be disowned before the angels of God.

Here the repeated phrase before the angels of God is another way of speaking of the immediate presence of God (see the parallel in Matthew 10:32, 33). We learn, therefore, with regard to angels, that they are always in God's immediate presence. What we also learn, however, is that believers ought to always be aware of an invisible world, the world of angels that is the world that really counts. So often we are aware of what men see and what they think but more important is what the angels see and what they think. When tempted to deny the Lord, think of the angels.
Revelation 3:5 is parallel in part
The one who is victorious will ... be dressed in white. I will never blot out the name of that person from the book of life, but will acknowledge that name before my Father and his angels.Also relevant is Luke 15:10, which we tend to think of as referring to angels but is really referring to God himself
In the same way, I tell you, there is rejoicing in the presence of the angels of God over one sinner who repents.
In Luke 1:19 Gabriel reveals that he stands always in the presence of God.

Angels are just, good, wise and discerning

2 Samuel 14:17, 20 “And now your servant says, ‘May the word of my lord the king secure my inheritance, for my lord the king is like an angel of God in discerning good and evil. May the LORD your God be with you.’ ” ... "Your servant Joab did this to change the present situation. My lord has wisdom like that of an angel of God--he knows everything that happens in the land."

(Also see 19:27 And he has slandered your servant to my lord the king. My lord the king is like an angel of God; so do whatever you wish.) 

These words spoken by the wise woman of Tekoa in two instances are really asides and we should be careful not to make too much of them. They do appear, however, to recognise a wisdom and discernment in the minds of angels that is beyond what we ordinarily find among men. Justice and goodness are also implied. These creatures are highly intelligent and they have not only a mental dexterity but also a moral integrity that remains untouched by sin. This enables them to know good from evil with great insight.

Angels do not marry or have sexual relations

Matthew 22:30 At the resurrection people will neither marry nor be given in marriage; they will be like the angels in heaven.

When Jesus says that at the resurrection, people will be like the angels, he cannot mean in every respect. He is narrowing down to the fact that they will not marry (or have sexual relations, presumably) which, far from being bad news, means that they will become like the angels who, being spiritual creatures, do not marry (or engage in sexual activity). Angels relate to one another as do brothers and sisters. This would seem to preclude the idea that the Nephilim of Genesis 6 were heavenly creatures rather than earthly. 

Angels are inferior to Christ but serve as God's messengers

Hebrews 1:4-7 So he became as much superior to the angels as the name he has inherited is superior to theirs. For to which of the angels did God ever say, ‘You are my Son; today I have become your Father’? Or again, ‘I will be his Father, and he will be my Son’? And again, when God brings his firstborn into the world, he says, ‘Let all God’s angels worship him.’ In speaking of the angels he says, ‘He makes his angels spirits, and his servants flames of fire.’ 

Christ's name is superior to that of the angles as although they are referred to as the sons of God at times, he alone is the Son of God. This is fitting because although he was made a little lower than the angels in the incarnation he became as much superior to the angels as the name he has inherited is superior to theirs. The very fact that all the angels worshipped the incarnate Son shows that he is God. (If all were worshipping the Son then none were doing anything else). Angels, in distinction from the Son of God, are like wind and thunder. They are messengers bringing God's message to earth. Like the wind they are invisible and like the lightning they are glorious. They are swift messengers from heaven.

Angels came and attended Jesus tempted in the wilderness

Matthew 4:11 Then the devil left him, and angels came and attended him.

Gill says that these angels came to Jesus in a visible, human form, as they were used to do under the Old Testament dispensation, which seems likely. It happened after the temptation was over; after Satan was foiled, and was gone. The timing shows that Christ alone had got the victory over him, without any help or assistance from the angels. Gill understands them as bringing him food of their own, as with Elijah, (1 Kings 19:5,-8) to satisfy his hunger and refresh him

Thus, says Gill, as the angels are ministering spirits to the heirs of salvation, both in a temporal and in a spiritual sense, (Hebrews 1:14 ) so they were to Christ. Nothing is more frequent with the Jews than to call the angels "ministering angels".

Spurgeon says that the enemy left him when he had shot his last bolt ... for a season .... So soon as the evil one had departed, angels appeared to fulfil a ministry for which they eagerly longed, but which the presence of the devil hindered. No doubt they had been hovering near, waiting their opportunity. These holy beings might not come upon the scene while the battle was being fought, lest they should seem to divide the honours of the day; but when the duel was ended, they hastened to bring food for the body and comfort for the mind of the champion King. It was a battle royal, and the victory deserved to be celebrated by the courtiers of the heavenly King. Let us behold, these angels, learn from their example, and believe that they are also near to all the warriors of the cross in their hour of conflict with the fiend. O Tempted but Triumphant King, thy servants worship thee, and ask permission and grace to minister to thee as angels did!

Mark 1:13 is parallel
and he was in the wilderness forty days, being tempted by Satan. He was with the wild animals, and angels attended him. 

Angels are very interested in gospel matters

1 Peter 1:12 It was revealed to them [the prophets] that they were not serving themselves but you, when they spoke of the things that have now been told you by those who have preached the gospel to you by the Holy Spirit sent from heaven. Even angels long to look into these things.

It is clear from Scripture that there is no salvation for fallen angels. They are very interested in anything to do with the salvation of human beings, nevertheless. They appear to be eager Bible students. It is not clear how Peter knows this.

Jamieson, Fausset and Brown say that these things are "the things now reported unto you" by the evangelistic preachers "Christ's sufferings and the glory that should follow" (1:11, 12 ). Tehy say that angels do not any more than ourselves possess an intuitive knowledge of redemption. "To look into" in Greek is literally, "to bend over so as to look deeply into and see to the bottom of a thing." As the cherubim stood bending over the mercy seat, the emblem of redemption, in the holiest place, so the angels intently gaze upon and desire to fathom the depths of "the great mystery of godliness, God manifest in the flesh, justified in the Spirit, seen of angels" (1 Timothy 3:16 ). Their "ministry to the heirs of salvation" naturally disposes them to wish to penetrate this mystery as reflecting such glory on the love, justice, wisdom, and power of their and our God and Lord. They can know it only through its manifestation in the Church, as they personally have not the direct share in it that we have. They quote Hofman in Alford, "Angels have only the contrast between good and evil, without the power of conversion from sin to righteousness: witnessing such conversion in the Church, they long to penetrate the knowledge of the means whereby it is brought about".

Angels will accompany Christ when he returns

Matthew 16:27 For the Son of Man is going to come in his Father’s glory with his angels, and then he will reward each person according to what they have done.

Mark 8:38 If anyone is ashamed of me and my words in this adulterous and sinful generation, the Son of Man will be ashamed of them when he comes in his Father’s glory with the holy angels.

Luke 9:26 Whoever is ashamed of me and my words, the Son of Man will be ashamed of them when he comes in his glory and in the glory of the Father and of the holy angels.

Matthew Poole says that Luke repeats the first two most perfectly, as here recorded. Mark expounds Luke’s words, where he saith that Christ shall come in his own glory, and in his Father’s and of the holy angels. By the glory of the holy angels is meant no more than attended by the holy angels, according to Matthew 13:41 and 1 Thessalonians 4:16 and other scriptures.

1 Thessalonians 4:16 says

For the Lord himself will come down

with a loud command,

with the voice of the archangel and

with the trumpet call of God,

and the dead in Christ will rise first.

There appears to be some parallelism here - the loud command is the voice of an archangel and can be pictured as the trumpet call of God. Christ calls the dead from their graves. He does so by sending his holy angels, led by the archangel, to gather the elect.

At the same time (Matthew 13:41) the angels will weed out all evil

The Son of Man will send out his angels, and they will weed out of his kingdom everything that causes sin and all who do evil.

Angels will be weeders out and harvesters at the end

Matthew 13:39, 41, 49 ... and the enemy who sows them is the devil. The harvest is the end of the age, and the harvesters are angels. ...

The Son of Man will send out his angels, and they will weed out of his kingdom everything that causes sin and all who do evil. ...

This is how it will be at the end of the age. The angels will come and separate the wicked from the righteous

We learn in this parable that the angels will be the harvesters of people at the end of the age. Sent by Christ they will weed out everything that causes sin and all who do evil. .. They will separate the righteous from the wicked at the end.

Spurgeon says on these verses

Now is the time of growing: the harvest hastens on, and the reapers are already chosen by the great householder. We may rejoice that angels, and not men, are the reapers. At what hour the consummation of the age (RV) shall come we do not know, but it is surely drawing nigh. ... This the Son of man will do with authority; the angels are simply the executioners of the wrath of the Lamb. ... The separation between “the wicked” and “the just”, who are in the kingdom, will be at the close of the dispensation. It will be accomplished by the messengers of God, the appointed angels: it will be done infallibly, readily, fully, and finally. The doom of the wicked is described in terms which are terrible to the last degree. ....

Matthew Henry says

The reapers are the angels: they shall be employed, in the great day, in executing Christ’s righteous sentences, both of approbation and condemnation, as ministers of his justice, ch. 25:31. The angels are skillful, strong, and swift, obedient servants to Christ, holy enemies to the wicked, and faithful friends to all the saints, and therefore fit to be thus employed. He that reapeth receiveth wages, and the angels will not be unpaid for their attendance; for he that soweth, and he that reapeth, shall rejoice together (Jn. 4:36 ); that is joy in heaven in the presence of the angels of God.

The angels of heaven shall come forth to do that which the angels of the churches could never do; they shall sever the wicked from among the just; and we need not ask how they will distinguish them when they have both their commission and their instructions from him that knows all men, and particularly knows them that are his, and them that are not, and we may be sure there shall be no mistake or blunder either way.

Angels shouted for joy when God created the world

Job 38:6, 7 On what were its footings set, or who laid its cornerstone - while the morning stars sang together and all the angels shouted for joy?

God questions Job as to where he was when God created the world. This leads to the reference to the angels adn creation. We know that the angels and all heavenly creatures were created before the creation of this world. Here we learn that the angels shouted for joy when God created the world. The morning stars must be another way to refer to the angels. Jesus is the bright and morning star (Revealtion 22:16) and they are morning stars. Stars speak of glory, purity and light and of constancy, permanency and the numbers points to the fact there are so many angels.

It is rare to find a reference to angels singing in Scripture but that is the implication here. Perhaps the cause of their rejoicing was the anticipation of the work of salvation for which this earth forms the theatre. It may have been simply to do with the creation itself.