19And by this we will know that we are of the truth, and we convince our heart before him, 20that if our heart condemns us, because God is greater than our heart, and he knows everything.
John uses another unclear demonstrative pronoun this. Likely, it refers back to verse 18 and the active love mentioned there. Such active love is the one assurance that we are walking with God like we should. If we have any hatred, ill feelings, or even neglect towards a brother or sister, especially those in need, then we are not living as God wants us to live. Our expression of love to our brothers and sisters confirms our faith in and obedience to God.
Love provides the assurance of our salvation and that we understand the truth and live it out. The connection of love and truth is significant. Truth refers to more than facts but gets to the heart of the gospel. It could represent the whole concept of faith in Jesus, who is the Truth (John 14:6). To say a person is of the truth means that person has aligned his or her life with Jesus in faith and obedience. The way of the devil and sin is the opposite and is the way of deceit, ending in judgment.
When love is absent or when our love is conditioned by selfishness, we must think deeply and listen to the Holy Spirit’s conviction. Convince (peisomen) has the sense of having a clear conscience and assurance that we are right with God. Heart (kardian) represents the inner person, our thoughts, will, mind, outlook on life, and the part of our being that communicates with the spiritual realm. It broadly refers to our whole conscious being. If our hearts are not full of unconditional love, we must ask ourselves if we are right with God or if we need to confess and repent from sin, especially pride, which shows up as selfishness.
We cannot fool God with our hidden attitudes and motives. People constantly negotiate and strategize how to get ahead in life. They live as if God does not know their secrets or see what they do in the dark. The last phrase in verse 20 refers to God’s omniscience. Nothing can be hidden from God (Psalm 139:1-4). That is scary news for those who think they can hide their sins. It is good news of assurance to those who put their trust in God. God will not leave us in the dark about our sin but will convict us so that we develop a sense of remorse and fear that will send us to God asking for mercy and forgiveness. God will also guide and empower us to live out the truth of love and convict our hearts with righteousness through the Holy Spirit (John 16:7-9). The only redemption from the problem of selfish love is the atonement of Christ and the transformation of our inner-most being by cleansing out the self and replacing it with love.