With any POD, have a major world religion with over a billion followers or more originate out of the pantheons and spiritual practices of any of the native peoples of the Americas.
What is your POD?
To spread across the Americas, you need fast communication links.
So you're saying that this world religion could simply be inspired by, or a branch off from, Native American religion? What I'm thinking is that the Roman Empire got taken over by a sect of Judaism, which was not a dominant religion within the empire but exerted some outsized influence due to profile-raising revolts and the people being deported everywhere. So maybe if an imperial entity had a similar troublesome American province which spawned a social/religious movement with broad appeal...out of the pantheons and spiritual practices of any of the native peoples of the Americas.
This could work-- a colonization of the Americas by a non-Christian Europe, or at least one without some hegemonic religious organization. OTL the friars were the first administrators and scholars of the Spanish New World, they or any similar org wouldn't let a rival religion emerge from under their noses.You could have Europe dominated by polytheistic faiths, probably Hellenestic in the south and various Celtic and Germanic ones further north. That might make them more amenable to other religions than in OTL when they were monotheistic. Even so, the influence of a religion from the Americas would probably be by some form of syncreticism rather than straight up conversion.