well, from a Christian perspective, everyone's a sinner. that doesn't mean that we aren't capable of making morally correct decisions or living in in a worthwhile manner.
what that means, is that we're not perfect. we mess up, and we fall short of God's glory. we're not flawless, omniscient, holy, or sinless. everyone, Christian or non-Christian, messes up and does things which cloud their hearts.
another way to say it is that our sin / imperfection / human-ness separates us from God. we can believe in Him, and come to know something of His presence and help in our lives, but to know Him personally is not something we can do in our present state. we need to go through Someone who is sinless, who knows God personally, and who is One with Him, that through this Person we might be forgiven, cleansed, and reconciled to God.
for a Christian to say that they are inherently better than anyone else is silly. no person, whatever faith they profess, is good, holy, or wise enough to know God and show others to Him. we all need help, guidance, direction, and mercy. and in the end, we all need grace. it's His grace, not our righteousness, which reconciles us to Him. i can't point to myself, and shouldn't. i should however point to the Son of God, who makes us righteous, right, and who lifts away the veil of sin and lostness between ourselves, and our Father.