Presactly. What Dave said.

DaveTWB, your argument implies that people who have had sex should not be allowed to be married. Or people who have looked at pornography. "No, I'm sorry, you can't be married. You coveted your neighbour's wife."
These things are apparently against the word of the bible. Therefore, by your logic, allowing those guilty to be married would undermine the Christian church.

Your argument also continues to rely on the presumption that the institution of marriage, and the Christian churche are inextricably linked. I contend that such is not the case.