Objections to the kinds of things Catholics regard as sinful all tend to proceed along the same line of thought. "There's nothing wrong with what these people want to do. They're only sins according to the bible." This argument so grossly misses a critical point as to be embarrassing, however. Sin is defined by the bible. What the bible says to be a sin *is* a sin. That's just what sin is.
Opponents frequently protest: "You can't *prove* the existence of God and you can't *prove* the legitimacy of the bible, so you have no right to stop people from doing what they want to do." But are they really so blind as to adhere to this argument? Imagine some person (let's call him Jones) wants to kill some other person (let's call him Smith,) because Smith owes Jones 5 dollars but won't pay him. We we supposed to let this happen? No? Can you *prove* that murder is wrong? "But it's different. You're hurting somebody. It's clearly wrong." Clearly. Just like all sins are clearly wrong. When it comes down to it, though, what means have you to prove that it is wrong except for the same dogmatic faith that you pretend to disdain?
But I suppose this post won't accomplish anything. Despite Atheists' insistence that they possess superior powers of 'logic' and 'reason' I'm sure they won't bother actually trying to disprove these arguments in any rigorous way. They'll just maintain their hypocritical faith-based position and move on.
EDIT: I have posted responses to some select comments. If you didn't receive a response, you probably posted something uninteresting. To those of you who posted arguments of the form "but the bible says x is wrong and x is clearly not wrong!" you are missing the point. What criterion are we using for wrongness here? I offered one: something is wrong if the bible says we ought not to do it. Have you a criterion you can offer that you can back up with anything more than the same faith you deny as legitimate when coming from a Christian?