There's something about sin that many need to understand. There're spiritual sins, and there're physical sins. There're sins you commit in dealing with other human beings, but there're sins you commit in dealing with God. Spiritual sins are the ones towards God.
For example, if you're proud towards people and against them, they may never know, because pride is a spiritual sin; only God sees it. And the Bible says, "...God resisteth the proud, but giveth grace unto the humble" (James 4:6). That means no one who's proud can really excel with God. You can't really walk with God as long as there's pride in your heart.
Until the light of God shines in your heart, and defines pride to you, you could continue living in pride and not know it. The sad thing is, the consequences for spiritual sins such as pride are very grievous, because spiritual sins are more dangerous than physical sins. This is why, as a child of God, you ought to continually search your heart with the Word, to rid it of any form of spiritual sin. The Bible says, "For the word of God is quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart" (Hebrews 4:12).
The Word of God checks your thoughts and your motives. Therefore, give yourself to the Word; attend church services regularly and be present at your group Bible-study meetings. During such meetings, through the in-depth teaching and study of the Word, your faith is built strong, and your heart is purified — cleansed from all unrighteousness. Jesus said in John 15:3, "Now ye are clean through the word which I have spoken unto you." The Word cleanses you from sin and gives you the power to live above sin.