I look at the history of Christianity, and I see *MILLIONS* of people doing things which, according to their upbringings, were acceptable, but which we, today, claim are unambiguously sinful. Were *NONE* of those people really Christians?
I think it's far too easy to believe that a thing is "plain" from the text of the Bible when it is, in fact, not even *true* of the text of the Bible. Assume I grant for the sake of argument that you, today, have it all right; everything you think is plain from a careful reading of the Bible is right.
In that case, not one person born before 1500, except for Christ Himself, has been clear on the whole thing. There are too many things which you, raised in a modern Western culture, take for granted as moral laws, and which make you understand the Bible very differently from people living two hundred years ago, let alone a thousand years ago.
So... either you're wrong, or they're wrong, and if the Holy Spirit genuinely informs people *ABSOLUTELY 100% OF THE TIME* when they are sinning, if they're Christians... then either you're not a Christian, or none of those people were.
Neither of these seems *REMOTELY* plausible to me. I am obliged to conclude that people do, indeed, sometimes simply not understand that something is a sin, despite sincere efforts to understand. This would be my understanding of the "sinful nature" we are told humans have; we simply *can't* listen all the time.
If, indeed, people "chose to ignore" things, then either this is the first generation of people with any *chance* of salvation, or God forgives that, too. [/B]