Christianity went through its killing-spree period when the best weapons were pikes and matchlocks (the Thirty Years' War). The fanatics of the time did their best, but their best just doesn't stack up very well against the power of a modern industrial state.
Oh, if we're recounting the history of Christian aggression, why stop with the Thirty Years' War? Why not trot out the Inquisition, the Crusades, and the Jesuit "invasion" of the New World?
All of which 1) took place a few hundred years ago, not yesterday; and 2) pale in comparison to the ongoing slaughter sponsored by godless communist regimes and the theocracies of Allah the Red-Handed.