1Jo 1:1 ¶ That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked upon, and our hands have handled, of the Word of life;
 2 (For the life was manifested, and we have seen it, and bear witness, and shew unto you that eternal life, which was with the Father, and was manifested unto us; )
 3 That which we have seen and heard declare we unto you, that ye also may have fellowship with us: and truly our fellowship is with the Father, and with his Son Jesus Christ.
 4 And these things write we unto you, that your joy may be full.
 5 ¶ This then is the message which we have heard of him, and declare unto you, that God is light, and in him is no darkness at all.
 6 If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth:
 7 But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.
 8 ¶ If we say that 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 that we have not sinned, we make him a liar, and his word is not in us.(KJV)

For such a short chapter there is so much in these verses. Verse 7, of course is such a precious verse. Our salvation is through the blood of Jesus Christ - no other way. Only the blood cleanses us from our sin. It is a shame so many try to remove the blood from our faith - that blood is precious. 

Then others don't realize the value of the blood. Too many try to wash away sin in the water of baptism. Some try to purify sin in the fires of purgatory. Water and fire won't cleanse us from sin - ONLY the BLOOD of JESUS will do that!

Then we look at verse 9. That is a precious promise. Once we are cleansed and saved by the blood of Jesus, we soon find we still have a sin nature that now wars with our new saved nature. We are still in this world and we get dirty. Once we are born into God's family He doesn't kick up out, but He will chastise His children, so the smartest thing for a child of God to do if he sins, is confess that sin to God, ask His forgiveness and let Him cleanse us from that sin, so He will not have to chastise us.  Confessing sin to a person will not help us - no one can cleanse us of sin except the Lord. If we sin against someone we need to apologize to that person and make restitution if needed, but our forgiveness and cleansing still comes from God, not man.