Why progressive revelation?

You're really asking 2 distinct questions here, so let me take each one separately.

Schuhart wrote: »

Why would God start out with just one group of people? Does this mean that none of the others have a chance of redemption, until Jesus turns up? Even when Jesus turns up, do I still have a chance of redemption if I live somewhere remote from the message where we either never heard of Christianity, or only heard of it as the wrong religion? Surely this means either that God is unfair (as people who couldn’t reasonably access his message get damned) or that Christianity is unnecessary to be saved (as only people who’ve heard the message in detail need worry about it).

Firstly, let me point out that redemption is an undeserved gift, not a right. The Bible teaches that we all sin and that sin has bad consequences. Therefore if God had offered nobody the opportunity of redemption, we would still have no right to complain. It's bit like picking out a beggar in Africa and giving him money. Are you doing something kind, or does that give other beggars the right to complain how unfair you are that you selected one beggar and therefore treated the others unfairly? Therefore I do not think it must follow that God has to give everybody an equal opportunity for redemption.

My own personal belief (I stress that this is highly speculative, and other Christians may well disagree with me) is that people in all cultures and societies have received some revelation of God, no matter how imperfect. I believe God is a just God and that He will judge everybody by the light they have received - although I must stress that most people in all cultures have failed miserably to live up to the light they have received.

You ask a very thoughtful question in that you ask if "only people who’ve heard the message in detail need worry about it". This certainly identifies the weakness in the position of those Christians who say things like, "The only sin God will judge you for is rejecting the Gospel". If that were so then missionaries would be doing people a disservice by preaching the Gospel to them. Far better to leave them in ignorance so they can't be judged for rejecting a Gospel which they've never heard.

My own opinion is that preaching the Gospel to a previously unreached person will give them a second opportunity to receive redemption since they have probably failed to live up to the light they have received. So, I am not ruling out the possibility of someone who has never heard the Gospel being saved, but I think that the possibility becomes much greater when they hear the Christian Gospel.

Also, what is the quality in humanity that suddenly made us fit for the final message two thousand years ago? For the sake of argument, Greeks seemed to be capable of chewing the fat about philosophy for hundreds of years before Jesus arrived – suggesting that humans already had the capacity to handle whatever concepts needed to be thrown at them.

So why all the cloak and dagger stuff? Why not supply mankind as a whole a definitive rulebook from day one?

This is the progressive revelation question. This probably won't please you, but I'm going, to at least some extent, fall back on the old standbys of faith and mystery.

I believe that God has arranged things in a way that has achieved the following aims:
a) For the maximum number of people to receive redemption.
b) For human free will not to be so compromised as to become meaningless.
My faith is that the method of progressive revelation achieved, and will ultimately achieve (for I believe the process is still continuing as we learn the lessons, often painful, that history teaches) the maximum results while balancing these two aims.

It is true that Greek philosophers chewed the fat over philosophical principles for many centuries, but that did not produce the results in people's lives. For example, at one time Islamic scholars studied the Greek philosophers much more closely than Christians, yet today we would not have the freedom to carry on this discussion in a public forum if we were in Saudi Arabia. God's method of progressive revelation has produced a situation where those societies where the Gospel has been preached most also happen, for the most part, where we see tolerance and rational discourse as basic values.

I see the same situation in respect to slavery. Yes, it would be easier for Christians in internet fora if the Bible contained a clear unambiguous declaration that all forms of slavery are wrong. But the fact is that slavery is a symptom of something much more serious - the all too human tendency to treat others as inferior or even as less than human. The New Testament, by stressing that slaves and masters are brothers together in Christ, made inevitable the eventual abolition of slavery. Do I wish it had happened quicker? Do I wish the New Testament condemned slavery more clearly? Of course! But my faith in God leads me to trust that, for some reason I cannot see, that God's way achieved the necessary result more effectively than any alternative.

Unsatisfying I know, but there you go!

Schuhart wrote: »

In fairness, I wouldn’t blame the Greeks for Saudi Arabia.

No, neither would I, but that is not my point. My point is that extensive exposure to Greek philosophy did not prevent a culture moving in a backward and oppressive direction. Mere pronouncements and philosophy are largely powerless to change human nature and societal values. Such change appears to occur best through a gradual process - hence progressive revelation.

Just look, for example, at what happens if you try to impose a good value (democracy) on people who are not ready for it. They simply use their democratic will to elect the biggest bunch of extremists they can find.