If you're asking what you call someone who joins a religion, then you just still call them by their name. But if you're asking how you call someone who's joined a religion, calling them should still mostly be the same. Just dial the number on your phone, they're not going to kill you.
An atheist
A martyr.
They can be either Atheists or Agnostics.
We call those people "Hypocritical".
The Careers call Peeta "Lover Boy".
Someone who practices Shinto is called a Shintoist or a Shinto adherent.
fertilization
Antitheist Atheist Nothingarian Skeptic Zendic
Probably called: A new Religion.
$20,000
Very confused. Religion is what you truly believe and what you practice through your lifestyle. EVERYONE has a religion. Atheism is a religion. There's even a religion for those who don't care about life or truth at all.
Someone who often interrupts or joins conversations without being invited or welcomed is typically referred to as an "interloper" or a "meddler."