The differences

On my way to Atma Jaya, I watched the television "spiritual speech" program  (idk, how to say Ceramah in English, pardon me :) . The main topic of the day was about the differences, especially the religious differences, and how's the right relationship between moslems and others. So much and too much limits and rules, i guess i already crossed the line, and broke the rules! Is it bad? Or good?

Soo many thought in my mind, did God really make the rules (or border) for us to have a relationship with others (nonmoslems) ?? Okay, i understood bout the limits, but why the rules not soo human? we are live and life with others, we born as social being, we have to respect others. But why even a little responses, like saying "Marry Christmas" to peeps who celebrate, is one of the prohibited words.

Pray for people with different religious is prohibited too, Why?????
It is kind of sin? Oh WHY??