what christian organizations mandate followers to have beards?

Question

I can only think of the amish. The orthodox churches don't even require the clergy to have them anymore.

Answer 1

Most of the more conservative Mennonite and Brethren groups do, as do the "old-calendarist" Orthodox groups. Remember, to have such marks requires that a church builds a strong connection between faith and works, something that many Christian groups de-emphasize (especially modern protestants). Roman Catholicism never really had the beard as a general mark of piety (though you do see it as a sign of contempt for the world amongst some monastics). That really only leaves you with the Orthodox and the Brethren/Mennonite groups having a theological support for such marks of piety. I don't think you'll find it anywhere else.

Answer 2

No mandate.