Either you withhold membership from all sinners or you withhold it from none. I'm pretty sure that sin is sin; and in Christianity it is the nature of man to be sinful. Is the man who drinks all day Saturday, confesses on Sunday, and lives fine until the next Saturday the better Christian than the one who "lives in sin"?
I think that churches should be inclusive rather than exclusive. Having the pastor decide which sins are allowable, and which ones get punished, is going to end up alienating people, and hurting the church.
I like Spooks points on marriage as well. It was only in the late Middle Ages that marriage became common for the common person. Even church marriages were viewed as more of a property contract than what we think of as marriage. People moved in together, lived together, had children all without the benefit of a church sanction. Even the early bans against married priests had more to do with inheritance laws (church lands passing out of church hands) than any moral objection to married priests. Back in the 1300 and 1400s, when the Catholic Church was the only Christian game in town, rules for parish priests included not being allowed to baptize their own children, and not being allowed to say mass if they were too drunk to recite the Latin (that was an INTERESTING history class).