According to my understanding,
Angels have free will. They can fall. They cannot be redeemed though. Angels have seen God and dwelt with him. When they fall away they cannot be redeemed they are cast out. They can still come and go, as Lucifer does in the book of Job, but they are not among heavens angels. If they break the laws of God too severely they can be cast into the abyss, which is apparently a region in hell. This is where Legion did not want to be sent.
Jesus, who is the Christ, did not die for sins of angels - but for the sins of man. Angels are already in their immortal form. If there is redemption for angels the Bible does not speak to it.
“And there was war in heaven:
Michael and his angels fought against the dragon; and the dragon fought and his angels, and prevailed not; neither was their place found any more in heaven.
And the great dragon was cast out, that old serpent, called
the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.”
Revelation 12:7-9
“Therefore
rejoice, ye heavens, and ye that dwell in them.
Woe to the inhabiters of the earth and of the sea! for the devil is come down unto you, having great wrath, because he knoweth that he hath but a short time.
…..And the dragon was wroth with the woman, and
went to make war with the remnant of her
seed, which keep the commandments of God, and have the testimony of Jesus Christ.”
Revelation 12:12, 17 KJV
“And they worshipped
the dragon which gave power unto the beast: and they worshipped the beast, saying, Who is like unto the beast? who is able to make war with him? And
it was given unto him to make war with the saints, and to overcome them: and power was given him over all kindreds, and tongues, and nations.”
Revelation 13:4, 7 KJV
“Be sober, be vigilant;
because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour: whom resist stedfast in the faith, knowing that the same afflictions are accomplished in your brethren that are in the world.”
1 Peter 5:8-9
……….And
the devil that deceived them was cast into the lake of fire and brimstone, where the
beast and the false prophet are, and
shall be tormented day and night for ever and ever.”
Revelation 20:10 KJV
“And
the angels which kept not their first estate, but left their own habitation, he hath reserved in everlasting chains under darkness unto the judgment of the great day.”
Jude 1:6 KJV
“Then shall he say also unto
them on the left hand, Depart from me, ye cursed, into
everlasting fire, prepared for the devil and his angels:”
Matthew 25:41 KJV
It has some to say about the subject
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