I Cor. 4:4 My conscience is clear, but that isn't what matters. It is the Lord himself who will examine me and decide.
It has often been said, "Let your conscience be your guide." There is the assumption that we all know the difference between right and wrong and we will sense guilt or shame when we are tempted to do wrong. While in principle this may be good advice, it simply does not work for many people.
Sin plays havoc with the conscience. Sin can deceive us, distort our perception of right and wrong, and destroy our desire to do right to the point where following our conscience can easily lead us into sin. It is not too hard to look at ourselves in the mirror and feel pretty good about what we see. We may think we are doing alright, when in reality we aren't. When our sense of right and wrong is dulled by sin, our standards are way too low. It is not how we see things that matter, it's what God says about things that matter.
The Lord is the one who will judge us and decide whether or not we are right before Him. The standard upon which He judges us is His holiness as revealed in His Word. He tells us clearly how we are to be, what we are to do, and what ought to be on our minds. It is the Lord we must please, not ourselves.
Can you look into the mirror of God's Word and still say your conscious is clear?