I have two questions so I would like to roll them into one so please answer.

Scientology is a religion based on the writings of a science fiction author. It is very hard to find information about the church that isn't either written by the church, or written by people who hate the church. So it is kinda hard to point you in the right direction to get some good information on Scientology. I suggest you Google "Scientology" and read some of the links that it provides you. You'll find that the debate is very heated.

As for how to come out as an Atheist to Christian parents, I'm afraid I don't have any advice because I have not been through that experience myself. Hopefully someone else here will be able to help you with that, but please know that you can come here for support at any time. :)

the exact answer to the first one is above

the way I told my parents was straight and to the point "I don't believe in your so called God, and Im an Atheist" we talked about religion for an hour and everything was fine, I hope your parents aren't so mellow-dramatic, or else there could be some family tension

I don't really know but you should just tellyour parent straight that your an atheist and tell them why it always i think it will work if your parents aren't stubborn like mine cuz for me i always have to make them remember i am one or they will make me go to the church and all that stuff and sometimes they just tell me that i don't have the right to be one :S