Um...duh...The Reformation.
And what about the reformation?
To my knowledge all the european states existing today pretty much already existed then during the reformation. None of them (none that i can think of at the top of my head) had to create a new state (and this is what the various conflicting Meo christian denominations have to do; come together, gather strength, go conquer enemies and create a brand new state). After several generations of war the roman catholics just had to accept that there will be some protestants living within their already existing nation, country, state.