Get Primary Religion?

[TranceBlossom]

Is there a way to easily get the primary religion of a Player, not just what the religion they founded is?

 

[LeeS]

If you mean by this the Religion followed by most of the player's cities, then no, there is no easy direct pre-provided method for that.
Nor is there a pre-provided method for determining which Religion a majority of a player's citizens follow.