Martinus
Emperor
I'm not saying that it's impossible to become the dominant religion anyway, but you'll end up having to fight to get your reward, while with other policies you get your reward instantly and surely.
That's not true for all other policies. Definitely Patronage requires you to fight for your reward. And many other bonuses (e.g. ones to trade routes, archeology digs, or research agreements) can also prove quite empty if you, e.g., get embargoed or someone beats you to the artifacts or everyone hates you.