because if our heart condemns us, God is greater than our heart, and knows all things.
“because if our heart condemns us” Can refer to past sins or feeling insufficient in accomplishing God’s work.
“God is greater than our heart, and knows all things.” Whatever we might feel about ourselves and our shortcomings, God’s Word supersedes our conscience.
Sometimes the enemy will make you feel guilty for the things you have done in the past, but the Lord through repentance has forgiven you those sins. We must not dwell in those things, but looking forward, continuing in doing God’s will.