[jabv]

I think lucozade's reply (just below yours) gets closer to why Sheen's argument matters at all (admitting that it is more of a, "Hey, have you thought about it this way?" than a serious argument, the latter of which Sheen also focused on) - whether we transfer the content to Jesus' followers or not, we still these condensed narratives containing historical claims as well as general teaching, and the claims are extraordinary, whether we attribute them directly to Jesus or to the followers. If the account in the gospel of Luke regarding the annunciation of Jesus' conception is false, then the rest of Luke's testimony about the words and deeds of Jesus is suspect.

Additionally, the great majority of Jesus' teaching depends on a context that admits unabashedly of a supreme Creator to Whom we owe, well, everything. Thus Jesus' teaching that lusting after a woman internally is tantamount to adultery only makes sense in the given Judeo-Christian context. So, even if we ignore claims of divinity and the origin of those claims, it's difficult to find a coherent moral message absent some claim regarding the existence of an ultimate Creator.

[danielam]

While I agree that it is impossible to take Jesus seriously without also taking seriously his claim to divinity, I do not understand the example you've given concerning adultery. Not everything that Jesus taught was a matter of revelation. Much of it can be arrived at with the use of unaided reason. In this case, adultery and lust are moral concerns that do not require an appeal to Jesus' authority. It is entirely possible for a non-Christian to come to the same conclusion just as it is possible to consider many moral questions without appealing to God. Whether something is good for human beings depends on human nature. God comes in when we wish to account for the existence of human nature (or anything at all) in the first place. Typically, those who base morality on arbitrary divine command hold to a mechanistic metaphysics that permits no other basis for morality.