Some say we cannot live withOUT sinning.
1Jn 1:9 If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.
1Jn 1:10 If we say we have not sinned, we make him a liar, and his word is not in us.
1Jn 2:1 My little children, I am writing these things to you so that you may not sin. But if anyone does sin, we have an advocate with the Father, Jesus Christ the righteous.
2) Christians are capable of not sinning because we have the Holy Spirit dwelling in us. But we still sin because of our nature (not because the devil made us do it). We really don't have an excuse.
3) If Christians refuse to admit they sin then they really are non-Christians. This is simply because we don't understand repentance.
4) If Christians fail to confess their sin, the Father will correct that situation. Pro 28:13 Whoever conceals his transgressions will not prosper, but he who confesses and forsakes them will obtain mercy. We simply will not prosper as Christians.