Hebrew 9:12 says ” Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtain eternal redemption for us.”
Now when He (Jesus Christ our Lord) went to heaven with His Blood, He placed it on the mercy seat. That is His throne and that is where He is sitting right now (Exodus 25:21-22). Mercy is something that God Almighty did by Himself to you through His son in replacement of death penalty.
For the Bible says all have sin and come short of the glory of God. (Read Romans 3:23). We all used to be sinners before we got born again. Now we are no more sinners but saints because we believe in Jesus. A good illustration is a thief who deserve to be in jail for his crime. In place of jail sentence he was released not because of his goodness but because he acknowledged his wrong and said I am sorry. So did Jesus took our place of judgement that we may go free on the cross (Read John 12:30-31).
So it does not matter what you did in the past. Only identify with God’s saving mercy for your life. And say no to satan! The reason why the Blood of Jesus is on the mercy seat is that it speaks of mercy and it also opposes all satanic accusations about your past, future and satanic powers against you as well. The Blood speaks and one of the voice of the Blood is mercy.