I recall reading a book years ago on game theory. Basically the game was simple. The guy hits and you don't, he gets two points, and vice versa. You both hit, nobody gets a point, you both play nice, and the two points are shared.
The best strategy turned out to be tit-for-tat, with the occasional mercy thrown in order to lure the other guy into a stragegy that didn't involve hitting you.
Turn the other cheek works just fine, as long as people remember that they only got two cheeks Justice requires that turning the other cheek is a ludicrous policy when what results is your head spinning around like a top, as the other guy collects his two points times after time after time.
Fair enough though if a Christian chooses to do that strategy on his own. It is cruelty on the Christians part, when he decides to choose that strategy for his neighbours as well.