Sources
Godot is the ultimate source on everything here, so it's good you asked her.
I am, dear Nihilistic one. Bow before me! :-)
PC - depends on what you want to do with it. It is a truly valid examination of where the trinity comes from? not at all, really. Far too much agenda there. We don't know where teh trinity came from; it's a new invention that is found no where else in the jewish faith, or so far as I know, any other religion. BUT if what you are saying is "this dude thinks..." then it's a good sources.
Sources are not good or bad for what they say, but how you use them, and only you know what you intend to say about it.
I suspect in religions there is always a serious measure of copy-pasting, but i'm pretty sure it's never deliberate. "oh, they have a stud god, let's copy it", more rather over time, your story includes things that are more interesting.
I mean christianity is by and large, judaism seen through a zoroastrain lens, or zoroastrianism seen through a jewish lens. but it was nearly 300 years in the making, and it just sorta (I think) happens, rather than anyone saying "let's copy".
It was rather blatant in some cases, though. Also, speaking of Acharya S, I noticed she was on the to-do list. You should go to town on this. (Hint hint nudge nudge.)
Part of me is dubious how much they are reflections of each other, and how much was "added" "invented" "redesigned" later to make them a single "religion.".
God, there is so much crap to write about, but yes, she (?) MUST have a page. god how I loath that whole movement. the "jesus is mithra" as well, which is sometimes in the same lump, and sometimes not.
so much to write!
Actually, that is the "Jesus is Mithra" stuff.
Ohhh, though they were two different things. goodie. this must be attacked.