I think we feel as though by calling ourselves sinners, we are keeping ourselves humble. But humility is not self-degradation; it is self-forgetfulness. Instead of focusing on how dirty and rotten and filthy we are, we should be focusing on how beautiful and incredible and holy God is.
Yes, there is a point in which we have to realize our sinfulness, to stand before a holy God and weep at our own unworthiness, to acknowledge the mess we're in and say God, I can't do this without you. And yes, it is important to always remember the pit that God lifted us out of so that we don't take our salvation for granted or get puffed up with pride.
What I have a problem with is this: getting stuck in the revelation of our sinfulness so deeply that we never move on to the revelation of ourselves as a new creature--not a sinner, but a holy, beloved child of the King (2 Cor. 5:17; 1 Peter 2:9-10). When the Spirit of God comes into our life, we are made new. But if we continue to harp on this notion that we are sinners, that is the identity we are going to live out of. "Oh, well I can't help but sin because I am a sinner." No. You are not a sinner. You were a sinner. Now, you are a child of God.
"For you did not receive a spirit that makes you a slave again to fear, but you received the Spirit of sonship. And by him we cry, 'Abba, Father.' The Spirit himself testifies with our spirit that we are God's children. Now if we are children, then we are heirs--heirs of God and co-heirs with Christ, if indeed we share in his sufferings in order that we may also share in his glory." -Romans 8:15-17
"Both the one who makes men holy and those who are made holy are of the same family. So Jesus is not ashamed to call them brothers." -Hebrews 2:11
The Holy Spirit of God in you. You have authority. You have power. You have freedom. Your sins have been forgiven, wiped away as though they never were. Don't let the enemy take your identity away from you. Don't let him hold guilt over your head. We may still stumble, but sin does not define us anymore. Jesus does.