Marcion was a second century Christian who believed there were two gods: the God of the Old Testament, and the God of Jesus Christ, the Father. As many will notice, this is very different from orthodox Christianity, which saw a continuation of Jesus from the Old Testament. Marcion accepted the God of the Old Testament was real and was the God of the Jewish people, but he had nothing to do with Jesus. Marcion identified Yahweh as a demiurge, a strict authoritarian, but also a cosmic bungler who created the evil material world that existed, from which Jesus would rescue us.
Marcion was hugely influential. He was the first to collate a testament: a version of Luke and ten Pauline epistles. He likely wrote a number of Paul's letters; they still bear the hallmarks of his theology.
I don't for a second think Marcion was anymore likely to be correct than what later became orthodox, but if he had succeeded we may never have had the horrible strife between Jews and Christians. There would have been no fighting over the same set of scriptures; the two religions would have been entirely separate. Instead of this we have Christians saying that, you know what, those scriptures that you say are yours, all those promises God made? Well, they're actually OURS now, they belong to us. So you better shape up and convert to our way of thinking unless you want to go to hell.
It should also be clear that Marcionite theology has a far better way of explaining all the evil in the world: it's the product of a bad god. This it shares with dualistic Zoroastrianism, where all the problems are the fault of the evil god Ahriman. It absolves the good god of blame. Monotheistic Judaism and Christianity don't have this luxury, as their god is purportedly all-loving. The best they can do is blame a figure like Satan, which is pretty weak because it doesn't explain why a good god is allowing Satan to do the things he does. This leads to the kind of monstrous apologetic this guy is touting. God is good, so everything he does is good, no matter how morally disgusting. It's a perfect example of how a religious doctrine can make people believe truly repulsive things.
