Matthew 9:10 (see also Matt. 11:19, Mark 2:15, Luke 5:30)
"The Son of Man has come eating and drinking, and you say, ‘Look at him! A glutton and a drunkard, a friend of tax collectors and sinners!’"
Throughout the Gospels, Jesus is pictured as the Son of God who spends time, even a great deal of time, with the known sinners of His day. In this Desiring God National Conference 2006 video, Pastor Mark Driscoll says,
"Many Christians don't have significant experience outside their Christian world. They listen to Christian radio; they listen to Christian music; they watch Christian television; they read Christian books; their kids go to Christian school; they go to Christian church; they go to Christian events; they go to Christian concerts; their friends are Christian; they go to community group or home Bible study with their Christian friends; they vacation with their Christian friends; and meanwhile their neighbors don't know Christ.I am very convicted by this, and I suspect many of you are, too. It is sad that so many of us think that holiness before God consists in being around or not being around certain people and situations rather than in the blood of Jesus alone. This legalism is both sickening and deadly, and our very own "evangelical" churches are the ones who have perpetuated it.
But the Bible says we're supposed to love our neighbor and we're supposed to practice hospitality, which is the welcoming of our neighbor. Well, to do that, we need to get to know our neighbor. And I think that is an attentiveness to the lives of lost people."
So I asked myself, and I ask you now, "When was the last time you spent significant time with an unbeliever? A sinner? A tax collector? An atheist? And if you can't remember, or you haven't, why not?"
(The best thing I've ever read on Christian liberty is a paper by Martin Luther, called Concerning Christian Liberty.)