1 John 3:19-20...This then is how we know that we belong to the truth, and how we set our hearts at rest in his presence whenever our hearts condemn us. For God is greater than our hearts, and he knows everything.
In my study Bible it says this: An oversensitive conscience can be quieted by the knowledge that God himself has declared active love to be an evidence of salvation. He knows the hearts of all-whether, in spite of our shortcomings, they have been born of him.
I just have to trust in Him, trust that he loves me, even when I fall short, even when I make mistakes, knowing that my salvation is by faith and grace.