Marijuana in it self isn't chemically or physiologically addictive, it's up to the individual whether or not they become addicted to it. It's just like Junk-Food, it tastes damn good, but if you over-do it, you'll have the consequences to pay.
Also, stop playing the "I'm a perfect christian kid because I won't ever smoke pot, I'll never become addicted because I won't try it" routine, it gets old really fast. Are you even in High-school yet, or are you only backing your argument because your parents said Marijuana is bad.