God Is Greater Than Our Hearts

You’ve probably heard it: the judge within you whispering (and maybe sometimes shouting) doubt and condemnation. But rest assured: that's not the final word on you, believer.
The book of First John is a lighthouse bright for the darkness and brimming with rich Gospel assurances. You can’t read that pastor-apostle John letter without being challenged and comforted.
John was probably Jesus’ bosom buddy of all the Twelve. Peter might have been the leader entrusted with the birth and formation of the new covenant Church, but John got Jesus’ heart and pastored like him. We get 5 of the 27 New Testament books from this John (Gospel, 3 letters, and the Revelation). St. John was a “specialist” in Christian assurance (Gospel of John 20:31; 21:24). Right knowledge is vital to a living, assured faith. He uses the word ‘know’ A LOT. For instance, he states:
“By this we shall know that we are of the truth and reassure our heart before him; for if our heart condemns us, God is greater than our heart, and he knows everything. Beloved, if our heart does not condemn us, we have confidence before God.”
1 John 3:19-21
 True faith is an abiding reality, no matter how small or mature. The measure of one’s faith is not dependent on the object of their faith.  True faith never goes beyond the pale into rank, damnable unbelief. Though related, assurance of faith and grace isn’t always a steady state. Just notice the two “ifs” above. It doesn’t mean we’re less saved. It just means that due to one or multiple variables (like personality, health, sin, or circumstances), we may be less sure at times than at others. Often a believer’s doubt or self-condemnation results from a guilty conscience. Real, damnable guilt was dealt with once and for all on the cross. Yet, that is one of the ongoing struggles for the Christian— distinguishing between guilt and genuine conviction of sin.
John helps pacify the troubled conscience with two assurances. Some Bible versions (NET and CSB) viably translate ‘heart’ (cardia) as ‘conscience’:

1. Looking Back: If we look back to the previous verses (3:18), it talks about how true faith demonstrates in visible sacrificial deeds towards the brothers, not just talking about it. If we can look back and see that we have shown love for God’s children, we can take that as a mark of divine love at work within us. We’re assured!
2. Looking Up: As Doug O’Donnell quips: “Our hearts don’t always align with our heads.” We go looking within or listening to ourselves or other accusations more often than not. John intercepts us as we’re headed into yet another one of our tailspins of guilt. The late Dr. James Boice summarized this as ‘faith must be fed by knowledge of what is true about God.’ In other words, we should look forward or out and up at God and his verdict; not our experiences. When our hearts pound the gavel again and again, must take comfort in God’s greatness and omniscience. God is greater than our hearts. He knows us better than we know ourselves. God’s omniscience usually (and rightfully) is a deterrent to sin, but here in 1 John it is comfort over our condemnation. Yes, God knows your woefully repeated failures. Yet, God knows what he has done for you, which is much greater than anything you’ve committed or omitted. Instead of defensively telling yourself or others the usual ‘God knows my heart’, tell your Accuser (which is what Satan means): “You are right. I am that and worse, but God, through Christ, has forgiven me, and I am dressed in HIS righteousness alone. God is greater than my heart.” Resist the accusations like that.

The words of "Before the Throne of God Above" ring true to the guilt-ridden heart: “When Satan tempts me to despair And tells me of the guilt within, Upward I look and see Him there, Who made an end to all my sin….”
 And then, be at ease even when your heart isn't as accused (verse 21). Enjoy confidence before God. Timidity, fear, and guilt are not the emotions that our good Father wants us to have. Go ahead, beloved child of God dressed like Jesus the Son, hop into your Father’s lap and ask away.
Dear Saint, rest— assured.