There is a condition in scripting called "CharacterReligion", so presumably in addition to a faction having a state religion and a settlement having a religious demographic, a character could nominally have its own religion it observes. Whether or not it's done via a command like that one I don't know, but I seriously doubt it. M2 was likely built off the Rome engine without most of the BI tweaks and added some in piecemeal, seeing as how it must have started development before Rome's release so it would be 1.5 years in the making by the time BI was finished. One thing is for sure, that nothing from Rome: Alexander is in M2/Kingdoms directly.
So you can try it, maybe it will work. I would suggest running a script using the CharacterReligion command to see if it worked after granting it in the descr_strat to a character that is in a settlement/faction with a differing religion.
Code:
monitor_event CharacterTurnStart CharacterIsLocal
and CharacterReligion pagan
historic_event it_worked false ;obviously have to define in strings file
end_monitor