Instead, I'm just going to assume that 'devoting oneself to the highest power' means 'selling out the the ones who won't kill you if you join them.'
Everyone has their own opinion on religion, of course, and therefore, it is impossible to create a world-wide peace when peace is agreement not to be enemies. For example, if a faith requires enemies to survive, its practitioners will continue to kill and maim and hurt others until the faith is dead or every last 'heretic' is no more than a memory.
Besides, organized religion defeats the purpose of free will, if you haven't noticed. That's why I'm the free and happy atheist that is completely stigmatized against any religion that doesn't offer the power to summon monsters based on a pact with the religion's deity.
Final Fantasy has some cool religions in it, ever hear of the Yevonites? Oh, wait, their leaders are corrupt and evil. Ever hear of the Covenant, a religious collective of alien races with one single goal? Oh, wait, that involves the total annihilation of all intelligent life in the galaxy. Star Wars has the coolest religion of all, though. May the Force be with you, always.