Christians repent their sins, or admit to their sins, and turn more toward God:

: to turn from sin and dedicate oneself to the amendment of one's life
a : to feel regret or contrition
b : to change one's mind 
Repentance is not a one time performance where a person dramatically asks for forgiveness for all their wrong doings, and then the curtain falls and they are "clean" forever, sinless as a newborn baby, unable to sin ever again. Humans commit sin, all the time. Pretty much all humans, regardless of their heritage, vocation, age, or religion. We commit sin in thought, word and deed, and half the time we don't even realize it. Envy is a sin. Wishing harm on another is a sin. Bigotry is a sin. Addiction is a sin because it's being tied to something outside of ourselves that we don't need for actual survival, which means it comes between us and our care for others, our responsibilities, our freedom, and God. (Smokers understand this; buying a pack of cigarettes as a priority even if you can't stand them and need the money for something else. Many people are addicted to coffee or soda but don't realize it's an addiction.) Arrogance and superiority are sins. Judging another person negatively is a sin, it blocks compassion. Road rage is a sin. When a man thinks they are naturally superior to a woman they are in sin, just as when a wealthy woman believes she is superior to a poor woman. Or either of those in reverse.

God is the Creator, not us; we don't get to say "Oh hey, you know those people you created, the ones that aren't the same as me? They didn't really come out good when you made them, so I'm not going to treat them as well as I treat the ones (like me) who came out GOOD. See? Look how you didn't do as good of a job on that part, and that part, and look at how they're kind of small in certain areas, see, you did a much better job on ME, and those who are like me."

Looking down on those who don't belong to one's church is a sin. Looking down on those who we think aren't "Christian enough" is a sin. Snubbing other church members or guests is a sin. We sin all the time in our little ways.

Repentance is not a one time deal, and believing that it is means ignoring all the teachings in the Bible about how humans are natural sinners. We can repent on Sunday, and feel completely cleansed and wonderfully renewed and redeemed, and then Sunday night we see a person on the television and think negative thoughts about them, or look down in judgment on someone walking down the road on the way home from Church. We require humility of ourselves (not of others, they're responsible for themselves). Repentance is a practice, since we are natural sinners, it's how we were made, and refusal to admit that is arrogance. There can be no repentance in arrogance, and we don't ever become superior beings because of our repentance. But we can be redeemed, thanks to God's mercy, when we make a practice of repentance.

Repentance is turning toward the Light so that we may see. Some of what we see is our own sins, and that's good, because then we can ask for forgiveness for them. When we sin we turn away from the Light, when we repent we turn toward the Light, and feel guilt and remorse, and this is a good thing. The more we turn toward the Light, the more we can see, and the more we will learn about ourselves and our sin habits.

Peace and light,