God's purposeful choosing not to remember sins is a sterling, godly act of wisdom, one that we are commanded to emulate. God does not forget our sins because He cannot any longer remember them, but because He actively chooses to forget them upon our repentance. Forgiveness has a condition that we no longer repeat the sin; to please God is to sin no longer. If we believe that God remembers our sins, it will be impossible to progress spiritually. We also need to put our own sins behind us, not clinging to their memory. Like David, we need to let go of our transgressions, feeling secure that God has blotted them out of His memory. We also must emulate Jesus Christ's ability to forgive and blot out sins of others, but remember the good things or good works done by others.