If the ponies did have a religion, most would probably have beliefs similar to the ancient Egyptians and Romans, they believed that their rulers were gods or demi-gods. I think some ponies would worship Celestia and/or Luna in a similar manner. There may be multiple beliefs in Equestria like our world. Maybe some would be centered around Discord or Tirek, for instance. Some might believe that there is a creator god like the Abrahamic religions or supreme gods like the ancient Greeks.
Exactly.
If Twilight was given a copy of The Bible she would definitely want to read it. She may not understand parts of it because it's not the history, religion, or culture of Equestria.
I don't think The Elements of Harmony would be replaced by The Elements of Love. They are similar, so, why change them?
That's nice to hear! At first I didn't like her but now I love her! She's not my absolute favorite, that title goes to Twilight, but she is one of my top ten characters.
Twilight probably wasn't written to be autistic, but she has some of the traits associated with autism. Introversion doesn't mean someone is autistic, it's way more complicated than that.
Twilight, Rainbow Dash, Applejack, Fluttershy, Pinkie Pie, Chrysalis, The Royal Sisters, Lyra, Octavia, Vinyl, Big Mac, Shining Armor, and Flitter have my favorite designs.