Please Help Me Remember This Book

This is a longshot, and I am not sure I really started reading it or if it was a dream.

The story involved the main character(s) traveling town some river in another time/place/dimention. Maybe aliens were involved, maybe the book had a religious theme. I acquired the book from the same bookshelf where I found a bunch of Left Behind novels, so the religious connection could be there.

I think the main character(s) kept encountering new and different peoples/creatures during the trip.

I wish I had more to go on. I know I did not finish reading it, and i want to find out the title so I can read the rest. Thanks for any help!

First guess, Riverworld by Philip Jose Farmer. It has aliens and something of religious themes, and fits your precis.

My first guess also.

If it’s Riverworld, know that there are three long sequels continuing the story from multiple viewpoints that eventually combine.

There is also a fifth book, but we don’t talk about it. At all. Ever.

Riverworld is it! The cover illustration of the golden bodies sealed the deal. Who whoula thunked, a book about a mystical world centering around a river…Riverworld.

Thank you all!