One idea is not exactly a foregone conclusion of the other, but it is one of the conclusions that you can reach. One of the arguments goes: If all men are made in God's image, and God is infinitely more important than any worldly matter, then all men are essentially equal in the face of the glory of God.

Interesting. I've seen a similar argument that humans are worms are more similar than humans and god, because both are creations. But it still requires an argument from the universally accepted doctrine, that is, I would not say that it is obvious or implied.

"All men are created equal" is a sentiment that had been simmering up and down in theologians for centuries before America was even discovered. Pope Gregory I (p533, at the bottom) put it in one of his moral treatises.

Very interesting. I don't think this actually raises it to the level of Christian doctrine, or widely accepted, but this is honestly much more than I expected.

John Ball (wiki IK, but it'll do as a summary) preached it as he rabble roused a peasant revolt.

First of all, props for using Wiki the same way I do - with some shame. As I understand it, John Ball preached social equality, that no one should be a gentleman as there was none in the garden of Eden. Not even the founders said that, they favored an equality of rights for free men.

But had the unintended effect of entrenching people against the very idea that some people are more beneficial/detrimental to your community than others when looking at their peers or downwards.

I think the problem is that 'equality' today is never qualified, as it should. All men are equal in the eyes of god? Sure. All men should have equal rights? OK. All men are of equal worth? Eh... not so much.