a new atheist and marriage

[FatAndFaithless]

A Poe is someone who fakes certain beliefs or viewpoints in order to make people who genuinely hold those viewpoints look bad.  It comes from Poe's Law, which states that any parody of fundamentalism is impossible to distinguish from genuine fundamentalism, because there are actual people who hold those views.  That's why it's always a question of whether or not someone is a Poe.  For example, someone comes onto the forum, parroting the most oversimplified, ridiculous versions of theistic arguments.  Option 1) they honestly believe those arguments, option 2) they are faking it to make theists look bad.  Option 2 would be a Poe.  The problem is that it's hard to tell the difference, since we've all met theists who actually believe those wacky things (I'm sure you can think of a handful on this forum alone).

A troll is just someone who wants to stir shit up without adding anything to a discussion, just being a douchebag.   They aren't mutually exclusive either.

As soon as I finished reading that first sentence, I was like, "Oh, is that like when they say that it's impossible to tell if someone who says something stupid in the name of religion is actually legitimately that batshit or if they're just faking?" But then you immediately followed it up with that. Why is it called Poe's law? Did Edgar Allan Poe have a satirical anti-religious bent or is it named after someone else called Poe or was there just no other better one-syllable name to give it?

It was coined within the last decade-ish, believe it or not.  It's one of those "internet laws" like Godwin's law or Cunningham's law, that only came about because of the internet and the mass communication it allowed.  A guy called Nathan Poe coined it on a Christian forum during a debate about creationism, which is extremely apt.