This is an oversimplification, but a good rough guide, IMO.
Put religions on a scale of cultyness from 1-10.
1= Unitarian universalists who allow ANYONE, who believes (or doesn't believe) ANYTHING to join them, atheists included.
10 = Jim Jones' Peoples Temple with literal poison Kool-Aid and one guy saying he is God.
On this scale I'd say cultyness starts to kick in from 5 on up.
Mormons & 7th Day Adventists: 6
Jehovah's Witnesses: 7
Scientologists: 8.5
David Koresh and the Branch Davidians: 9
Just my $.02. My numbers are completely subjective of course.
om