The modern church gets this backward, some will say, while in sin, "God knows my heart", yes He knows you have sin in there, the act proves it. We ought to stop accepting the excuse that God knows the heart to justify sin.
Someone once said to me that we are not liars just because we told one lie. If we were not already liars we could not tell even one lie. The outward lying is evidence of what is in the heart.
Christ died for man kind before most of us were born. He did that because He knew our sinful hearts. Those that think they have no sin because they don't carry out the desires of their heart must be hiding, hiding from God and hiding from others. Every sin is preceded by a heart that is sinful.
There are those who have never committed what they think are the big sins. The ones that destroy people's lives or cause devastating consequences. These people often think they do not sin, when in their heart dwells jealousy, anger and self-will that are seen by God and those who are discerning. Character can be seen even without acts, in the prideful expression of self goodness.
Self righteousness is a sin, that all by itself is enough to plunge someone into hell. There are many people like this in church gatherings today, they are hell bent on earning their way to heaven by their deeds or lack of sin. One cannot become born again, who thinks they can be good enough to gain heaven.
1 John 1:8-10 "…8 If we say we have no sin, we deceive ourselves, and the truth is not in us. 9 If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. 10 If we say we have not sinned, we make Him out to be a liar, and His word is not in us."
1 John 3:14-15 "…14 We know that we have passed from death to life, because we love our brothers. The one who does not love remains in death. 15 Everyone who hates his brother is a murderer, and you know that eternal life does not reside in a murderer. "
1 John 4:19-21
We love because he first loved us. If anyone says, “I love God,” and hates his brother, he is a liar; for he who does not love his brother whom he has seen cannot love God whom he has not seen. And this commandment we have from him: whoever loves God must also love his brother.
Our good deeds done in the flesh are nothing to God, they are even rejected by Him. It is only the good that Christ does in us that counts, because it is only Christ Who counts. He loves us, but not because of us, rather in spite of us. I know this is hard to hear, but we cannot love unless Christ loves through us.
Self righteousness is not love for others or God, its only love for self. We cannot love as God loves when we are self focused. Christ was "others" focused, He died for man kind while we were still sinners, while we had no love for Him, that's God's kind of love. Man tends to sacrifice a little for someone to gain the love of others. God sacrificed Himself to give His love to those who could not love Him back. He wants to create authentic love in us through Him.
Man loves to get something, Christ loved when we had nothing to give Him. When we love like Christ loved, then we will be letting Him work in us to be the love for others that He would be. We cannot take credit for our Christlike love, it is all Him in us.
Self righteousness is based on how good we think we are, but Christ righteousness is based on how good Christ is, a very big difference.
There can be no arrogance or grandiosity in those who have been changed into a new creation by Christ. We had to come to Christ over our own sinfulness, after that we no longer think of ourselves as good or better than others, our focus is on Who Christ is, that Perfect and Wonderful Savior Who did it all for us.
Galatians 3:13-15 "13 Christ redeemed us from the curse of the Law, having become a curse for us—for it is written, “Cursed is everyone who hangs on a tree”— 14 in order that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we would receive the promise of the Spirit through faith."
1 Peter 1:18-19
"Knowing that you were ransomed from the futile ways inherited from your forefathers, not with perishable things such as silver or gold, but with the precious blood of Christ, like that of a lamb without blemish or spot."