Good question. But theres something important which people should know ... If the followers may be doing something wrong, or if the followers of a particular religion may not be following something, ie in this case allowing people to turn the other cheek, it's not the religion that is bad, because the Bible has already set the rules, and its upto us, the followers to follow them.
Also, if somebody slapped me on the cheek, yes i would most assurdly say to them, to do my other cheek also. Wouldn't you like to set an example?
It takes a brave person to wake away from a fight. And if you allow a person to just slap you on the other cheek, it strikes them in their heart and in their conscience my friend. Let me tell you a quick story of an event that happened in India which a missionary reported to my Pastor last week...This is a true event...Listen carefully...
In India there was an Orphanage, and a local gang of theives rang one day all of a sudden during the daytime and said to the Orphanage that they are going to come straight away to rob them and told them to be prepared.
Well ... the Orphanage didn't know what to do, but there was a local missionary who was at the orphanage at the time, well ... short time later on the same day, the theives arrived on horses outside the gates of this Orphanage ... And they were celebrating and all happy, now what the Missionary did was she opened up all the doors, all the windows, everything...The theives walked upto the Orphonage seeing that all the windows and doors are all open and were getting to rob the place, thinking "this is too easy" ... Just before entering the orphanage he saw this missionary dressed in white kneeling at the door praying, and those thieves, in particular the leader, fell on his knee's with disgust thinking, what am i doing here? Stealing from little children?
Now this is why it's important to set an example, and Christianity does just this, regardless of what people say. Jesus says to turn the other cheek if somebody slaps you, he knows what he's talking about. I know of a story my sunday school teacher told me one time, this happened to her when she was young, listen up ...
She was at school and one of these bullies (a girl) came upto her and slapped her on the cheek, my sunday school teacher turned her face to her other cheek and said to slap her on the other side also, and you know what? The bully bursted out in tears of disgust of herself and ran away. The next day she came to my sunday school teacher and asked her to forgive her, and they became good friends.
Now see ... what kind of a person would she have been if she slapped her back and retaliated, it wouldn't have helped right? Doing the right thing what the Bible said, ended all problems, and infact made the two friends!
I hope this helps.