I wouldnt go Protestant or Reformed. I no CB into Circassia and flip to Orthodox (best religion in the game, tbh. Works well with religious- all you're missing out on is russia, and... you arent conquering russia anytime soon), and invading the Crimea, Caucauses, and Tartar lands helps you build up power without causing AE and lets you conquer your way to the second Italy- India.
Thats always fun.