Just a quick question...why is it such a bad thing to use something developed/owned by an atheist? That doesn't make something inherently bad or evil. If you seriously are going to be so shallow, you may want to do some research into numerous modern medical and scientific discoveries and inventions, many of which are developed and patented by non-Christians. Many medical advances were developed during WWII by the Nazis using methods that are abhorrent and evil, but we still use them today to save lives...does that mean that when you go to have surgery, you are being morally dishonest?
Yes, facebook is a powerful tool and increasingly popular...I honestly disagree with the ability it gives to children to access bad material, and I am deeply disturbed by the impact it has had on my generation throwing away their personal privacy on the internet. But is the fact that it's owner is atheist making it superbly evil? I don't think so.
Also, I'm kind of disturbed by the concept of isolating yourselves from all other non-Christians by forming a special social network-alternative. That's great to have a network, but by saying you want to essentially create your own special world, you are only contributing to the world's lack of communication and understanding among different groups. I's also a little bit self-righteous and egotistical to think you are "above" being part of an "atheist" social network, in my opinion.