by Matt Slick
It is not an issue of whether or not God will let the fallen angels and Satan repent. When we say "let them repent," it implies that God will allow them or give them permission to change their ways. It also implies that they might actually want to change. But the problem is that the demonic forces will never want to repent of their sin. In their rebellion, they became evil. Evil is the opposite of God's holiness. It is the desire to do that which is against God, to inflict pain and suffering, and to have extreme malice towards anyone. Out of such a fallen state, no good can come. Therefore, it is not possible for the demonic realm to repent because they will never want to.
Furthermore, there is no atoning sacrifice by which sins of the demonic realm could be removed. We, as people, have the atoning sacrifice of Jesus who is God in flesh (John 1:1, 14) and who bore our sins in his body and the cross (1 Peter 2:24). He is the propitiation, the sacrifice that turns away the wrath of God (1 John 2:2). The Scriptures clearly teach us what Jesus did for us. But, there is no Scriptural support for the idea that the atonement covers the demonic realm.