I posit that Christianity would have been better off if Mercianism had won.

A major source of doubt, as well as a large portion of the ills you ascribe to doctine today come from having to try and reconcile yahweh and Jesus. Having to reconcile the man who healed the lepers with the figure that invented cancer, drown the world and slaughtered egypts children.

Mercianism, with it's separation of Yahweh and Jesus, had it won out, would have laid a stronger foundation for a more benevolent church. The figure of Jeaus coming down to try and fix the wrongs put into place by a slightly malevolent creator god solves many inconsistencies both in the cosmology, but also in the theology.

The great commission still might have been enough for christianity to gain its foothold woth the sword for a few millenia, but an ability to disconnect from old testament dogna would also make the loving message of Jesus far more compatible with the realities of a growing, peaceful world.

And as a bonus you could still keep the carrot stick of hell/heaven by saying that evil Yahweh gets to send you to hell unless you call upon benevolent Jesus's protection.