Why Can't Christians Agree on Doctrine?

Michael Patton tries to answer this question here. My comment below his post offers a better explanation for why they disagree, and there's even more to it than what I said...

Michael, the real reason why other Christians don’t agree with you is because of the nature of a history itself along with the fact that God purportedly revealed himself in the ancient past. My argument is that if God did reveal himself, he chose a poor medium (history) and a poor era (the ancient past) to do so, and that makes an omniscient God look stupid (sorry).

We have a hard enough time understanding one another living in today’s world. We disagree about everything and we are constantly correcting misunderstandings about what we have said. So it stands to reason that this is compounded when we try to understand the literature of the ancient past. This is just obvious to me.

Of course, if God wanted to communicate more clearly and he could foresee that Southern slavery and witch hunts would result because he wasn’t clear, he could’ve said “Thou shalt not own, buy, sell, trade or beat slaves of any kind,” and said it often enough that believers could not misunderstand. He could’ve done the same with witch hunts and avoided the Galileo debacle as well. Genesis 1 could’ve started out by stating more clearly the nature of creation too. [If you’d like, I could show you how an omniscient God could’ve communicated better, and I only have an IQ of 160, again, sorry].

What’s the alternative? For God to reveal himself today on the great issues that divide the church. How could he do this? Through miracles and the church’s recognition of a 14th Apostle “like unto Paul.” In the meantime the disunity of the church speaks against the existence of the illuminating work of the Holy Spirit who has not done his job down through the centuries, and therefore provides evidence the Christian faith is a delusion, again, sorry.