1 Peter 1:10-12 clearly tells us that the grace of God in Christ Jesus was given to us only. This kind of grace was never allowed to angels in heaven so they long to look into these things.
10 Concerning this salvation, the prophets, who spoke of the grace that was to come to you, searched intently and with the greatest care, 11 trying to find out the time and circumstances to which the Spirit of Christ in them was pointing when he predicted the sufferings of the Messiah and the glories that would follow 12 It was revealed to them 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.
Why do you think God did not allow them the grace of Christ – the forgiveness of sin? There are many clues in the Bible as to why it is so. One of the prominent verses is found in Jude 6, “6 And the angels who did not keep their positions of authority but abandoned their proper dwelling—these he has kept in darkness, bound with everlasting chains for judgment on the great Day.”
God never forgave the sins of fallen angels who rebelled against Him and abandoned their heavenly place. He kept them in darkness until the Great Judgment Day. This might have been closely related to the account in Genesis 6(Read previous post titled “Nephilim - Fallen Ones”).
What can we say? This kind of God’s decision belongs absolutely to His Sovereignty and Providence. We cannot say to God, “why did you desert those angels?” But we can say “why do You save a wretch like me, Lord?” Do you want to know why? Here is the answer for your question in the following verses in Ephesians 1:3-14 and read them with patience.
3 Praise be to the God and Father of our Lord Jesus Christ, who has blessed us in the heavenly realms with every spiritual blessing in Christ.
4 For he chose us in him before the creation of the world to be holy and blameless in his sight. In love
5 he[b] predestined us for adoption to sonship[c] through Jesus Christ, in accordance with his pleasure and will—
6 to the praise of his glorious grace, which he has freely given us in the One he loves.
7 In him we have redemption through his blood, the forgiveness of sins, in accordance with the riches of God’s grace
8 that he lavished on us. With all wisdom and understanding,
9 he[d] made known to us the mystery of his will according to his good pleasure, which he purposed in Christ,
10 to be put into effect when the times reach their fulfillment—to bring unity to all things in heaven and on earth under Christ.
11 In him we were also chosen,[e] having been predestined according to the plan of him who works out everything in conformity with the purpose of his will,
12 in order that we, who were the first to put our hope in Christ, might be for the praise of his glory.
13 And you also were included in Christ when you heard the message of truth, the gospel of your salvation. When you believed, you were marked in him with a seal, the promised Holy Spirit,
14 who is a deposit guaranteeing our inheritance until the redemption of those who are God’s possession—to the praise of his glory.
Once again, “Praise be to the God and Father of our Lord Jesus Christ, who has blessed us in the heavenly realms with every spiritual blessing in Christ.” Let’s praise God for what He has done for you and me. Amen and amen.