God is love and love is God. He love us so much that he was willing to sacrifice his life for us. He took our burdens to Calvary to pay a price of Death for us.
When we sin, What would atone for us? Only under his precious blood. When we accept the word of God (bible) we are no more ourselves we become the word of God, when we accept the word of God it is God the spirit in us again, whatever we did in the past or present is no more in remembrance because we are under the shed blood (the word), once we confess our sins he will forgive us.
God is not looking at us from what we did in the past, he love us before we first love him and is looking at us through his blood. Once you repent (change of mind into his mind) and ask for forgiveness he remembers our sin (mistakes etc) no more.
Sometimes things maybe hard to explain because God ways are not our ways, his thoughts are not our thoughts, so all we have to do is just believe.
BE IT DONE UNTO YOU AS YOU BELIEVE.
If we believe he don't remember it no more, well he don't, if we believe that we are lost and are sinners, then we are.
Its our acceptance of God whatever we accept and believe to be, that will be.