I'm not sure if this is the right place to ask...

Why Christians prefer to marry a fellow Christian? Is this has something to do with the teachings or it's more related to personal thingy?

I'm a Buddhist myself thinking of converting but i would like to know more. Thank you for your advice.

I know. But can a Christian marry a non believer?(I know yes u can, but it is encouraged by the religion?) What if she/he does. Will he/she be subjected to scorn or treated as a traitor to the religion? That's all i want to know.

No scorn but you will have more trouble in your relationship. Non-Christians are spiritually dead (i.e. they don't have the Holy Spirit living in them). So being in a relationship with one is like being in a relationship with a dead person.