What's your definition of a "Christian"?

I've been reading a book written by Mike Yankoski titled "Under the Overpass ~ A Journey of Faith on the streets of America" and was challenged by his question of how I would define a Christian.  Before I could begin to answer, he asked; "Is it broad enough to encompass the drug dealers, pimps, prostitutes, and broken people of the world?  Jesus said that He came to heal the sick.  Drug addicts are messed up the same as liars are messed up, just the same as all humans are messed up.  We all need Jesus.  We all struggle with ways in which sin plays itself out in our lives.  What's worse?  To not do dope or to not love your brother?  Why do we kick drug users out of the church while quietly ignoring those who aren't dealing with other, equally destructive sins?  Why do we reject the loving, self-sacrificing, giving, encouraging, Jesus-pursuing drug addict but recruit the clean, self-interested, gossiping, loveless churchgoer?  Which one do you suppose Jesus would rather share a burrito with under a bridge?"
This resonates loudly within me...and I'm sure for those who share burritos under the bridge too!