then ı can say..islam doesnt want to kill person who swears islam but saudi arabia does...?
No, I dont think you understand, the rulings change from time to time, i.e. for example, a woman has to pray, but not when she is having her period. Does that mean Islam has changed? No, it means that the rulings change sometimes and somtimes they do not.
Similarly Islam might teach x but only when the right circumstances are in place.