Thus when someone approaches us and posits that a certain thing we do is a sin - we welcome the critique since we hate the idea of not following the commandments of our Lord much more than the temporary embarassment of being confronted with our own sin. Since the true believer frequently studies the Word of God and prays, and they keep the Lord in their thoughts continually and have the Holy Spirit dwelling within them, they may realize from time to time sins in their thoughts, words or deeds, and these evoke the same response.
The Bible tells us that the response to sin must be repentance.
and
While we all fall short of the glory of God, and our human nature is that we are born into sin, the Bible tells us that we will not live a sinless life, that even the most faithful among us will occasionally sin, sometimes not so serious a sin, sometimes a grave sin. We may find ourselves sometimes repeating a sin that we have confessed before. That being said, if we find ourselves having little or no success at all in avoiding repetition of our past sins, the professing Christian should really consider the condition of their soul - have we really put off the "old man", are we born again ? Anyone professing Christ while they continually and habitually commit grave sins for which they are not repentant is clearly not convicted of their own sin in their heart, they do not fear the Lord, and they actually are an unbeliever. Many Christians profess Christ outwardly, but are unregenerate sinners, unbelievers, and this is evidenced by their habitual, grave sins that display a hatred of God's Word and their rejection and opposition to it.
Additionally, as Paul speaks in Romans 7, even those who are regenerate and born again, will sin. The difference is that they do not want to sin. They take no pleasure in sin, their pleasure is in pleasing the Lord because He has put a heart of flesh in them to give them that desire. Oh, there may be some initial "pleasure" in sinning, but it is fleeting because sooner or later, they have to come to grips with knowing they have sinned against the Lord that they love. Then comes the struggle many know so well of coming to repentance, to quit struggling with God and giving control over to Him in that temptation to obey Him rather than our sin nature. And oh, what blessed peace there is then! And we know that this cycle will be repeated, over and over, but as it is, we also know that He is conforming us more into His image.
Contrast this process to the unregenerate who thinks they have to do all these things to not sin. That it is up to them. They have a pride in all that they do or can do, in order to live "holy" lives. Instead of having a great desire to obey their Redeemer, knowing they are unable in and of themselves, they look to the things they can do or say or touch or eat, or whatever and put their trust that God will be more pleased with them if they do so.
The gospel is simple: He is a holy God and we are not and can never be and we need Him alone to fix what is broken in us. So simple, but so difficult.
Amen.