Angels holy and unholy

There are at least three references to holy angels in the New Testament.

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. 

Revelation 14:10  ... they, too, will drink the wine of God's fury, which has been poured full strength into the cup of his wrath. They will be tormented with burning sulfur in the presence of the holy angels and of the Lamb.

By implication fallen, non-elect angels are not holy. The holy angels, Gill notes, will be judges and will condemn unbelievers to everlasting burnings and pronounce the sentence on them. They will gather them out and seperate them from the righteous, cast them into the furnace of fire, will be spectators of their punishment and rejoice at it. The sight of their power and glory will increase the torment of the sufferers.

Angels rejoice when sinners repent

In Luke 15:10 it says that

... there is rejoicing in the presence of the angels of God over one sinner who repents.

If that is read carefully, it must mean thhat God rejooices when sinners repent. Undoubtedly the angels rejoice too.

Angels revealed and announced the resurrection of Christ

Matthew 28:2-7 There was a violent earthquake, for an angel of the Lord came down from heaven and, going to the tomb, rolled back the stone and sat on it. His appearance was like lightning, and his clothes were white as snow. The guards were so afraid of him that they shook and became like dead men. The angel said to the women, "Do not be afraid, for I know that you are looking for Jesus, who was crucified. He is not here; he has risen, just as he said. Come and see the place where he lay. Then go quickly and tell his disciples: 'He has risen from the dead and is going ahead of you into Galilee. There you will see him.' Now I have told you."

Luke 24:2-7 They found the stone rolled away from the tomb, but when they entered, they did not find the body of the Lord Jesus. While they were wondering about this, suddenly two men in clothes that gleamed like lightning stood beside them. In their fright the women bowed down with their faces to the ground, but the men said to them, "Why do you look for the living among the dead? He is not here; he has risen! Remember how he told you, while he was still with you in Galilee: 'The Son of Man must be delivered over to the hands of sinners, be crucified and on the third day be raised again.'"

Angels are real personalities

In Luke 1:19 Gabriel says to Zechariah, "I am Gabriel. I stand in the presence of God, and I have been sent to speak to you and to tell you this good news." He has a name and can speak and refers to himself in the first person. He cannot therefore be a mere natural force or a psychological phenomenon. If we believe the Bible, we are compelled to believe in angels.

Angels strengthened Jesus as he came to the cross

Luke 22:43 An angel from heaven appeared to him and strengthened him.

Matthew 26:53 Do you think I cannot call on my Father, and he will at once put at my disposal more than twelve legions of angels?

Only Luke mentions this. As the angel appeared only to Jesus it may be wondered how Luke knew. It is suggested that such a change came over the Saviour that it was obvious to the disciples who then passed it on, Luke discovering ti when he wrote his Gospel.

Matthew Henry says of how when Christ was in his agony and there appeared to him an angel from heaven, strengthening him that this was a part of his humiliation - that he was thus strengthened by a ministering spirit.

Angels tell people not to be afraid when they appear

Genesis 21:17 God heard the boy crying, and the angel of God called to Hagar from heaven and said to her, "What is the matter, Hagar? Do not be afraid; God has heard the boy crying as he lies there.
Luke 1:13 But the angel said to him: "Do not be afraid, Zechariah; your prayer has been heard. Your wife Elizabeth will bear you a son, and you are to call him John.

Luke 1:30 But the angel said to her, "Do not be afraid, Mary; you have found favor with God. 

Luke 2:10 But the angel said to them, "Do not be afraid. I bring you good news that will cause great joy for all the people. 

Matthew 28:5 The angel said to the women, "Do not be afraid, for I know that you are looking for Jesus, who was crucified. 

Angels often startle people and make them afraid when they appear

Daniel 10:4-8  On the twenty-fourth day of the first month, as I was standing on the bank of the great river, the Tigris, I looked up and there before me was a man dressed in linen, with a belt of fine gold from Uphaz around his waist. His body was like topaz, his face like lightning, his eyes like flaming torches, his arms and legs like the gleam of burnished bronze, and his voice like the sound of a multitude. I, Daniel, was the only one who saw the vision; those who were with me did not see it, but such terror overwhelmed them that they fled and hid themselves. So I was left alone, gazing at this great vision; I had no strength left, my face turned deathly pale and I was helpless.
Luke 1:12 When Zechariah saw him, he was startled and was gripped with fear. 

Luke 2:9 An angel of the Lord appeared to them (the shepherds), and the glory of the Lord shone around them, and they were terrified.

Matthew 29:2-4 There was a violent earthquake, for an angel of the Lord came down from heaven and, going to the tomb, rolled back the stone and sat on it. His appearance was like lightning, and his clothes were white as snow. The guards were so afraid of him that they shook and became like dead men.

Gill notes how in the case of Zechariah he was troubled, and fear fell upon him; for such appearances of angels were not now so common as formerly: and when they were more usual, generally had such effects on the minds, even of good men and in the case of the shepherds - at the sight of such a personage, and at such unusual light and glory about them: they ... not used to such appearances ... were awed with the majesty of God, of which these were symbols, and were conscious to themselves of their own sinfulness and frailty.

Angels come with good news from God

Genesis 19:9, 10a ... "Where is your wife Sarah?" they asked him. "There, in the tent," he said. Then one of them said, "I will surely return to you about this time next year, and Sarah your wife will have a son."

Luke 1:11-17 Then an angel of the Lord appeared to him, standing at the right side of the altar of incense. When Zechariah saw him, he was startled and was gripped with fear. But the angel said to him: "Do not be afraid, Zechariah; your prayer has been heard. Your wife Elizabeth will bear you a son, and you are to call him John. He will be a joy and delight to you, and many will rejoice because of his birth, for he will be great in the sight of the Lord. He is never to take wine or other fermented drink, and he will be filled with the Holy Spirit even before he is born. He will bring back many of the people of Israel to the Lord their God. And he will go on before the Lord, in the spirit and power of Elijah, to turn the hearts of the parents to their children and the disobedient to the wisdom of the righteous - to make ready a people prepared for the Lord."

Luke 1:19 The angel said to him, "I am Gabriel. I stand in the presence of God, and I have been sent to speak to you and to tell you this good news.

Luke 1:26-33 In the sixth month of Elizabeth's pregnancy, God sent the angel Gabriel to Nazareth, a town in Galilee, to a virgin pledged to be married to a man named Joseph, a descendant of David. The virgin's name was Mary. The angel went to her and said, "Greetings, you who are highly favored! The Lord is with you." Mary was greatly troubled at his words and wondered what kind of greeting this might be. But the angel said to her, "Do not be afraid, Mary; you have found favor with God. You will conceive and give birth to a son, and you are to call him Jesus. He will be great and will be called the Son of the Most High. The Lord God will give him the throne of his father David, and he will reign over Jacob's descendants forever; his kingdom will never end."

Three obvious examples are the announcements of the births of Isaac, John adn Jesus. Perhasp that of Samson in Judges 13 could be added.

Angels always obey God

Psalm 103:20, 21 Praise the LORD, you his angels, you mighty ones who do his bidding, who obey his word. Praise the LORD, all his heavenly hosts, you his servants who do his will.

Instinctively and immediately angels always obey God's commands. This is the main basis for the part of the Lord's prayer wherewe are to ask that God's will be done on earth as in heaven.

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 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.