Hmm, well I really don't know what sugar-coated word I could use that could be seen as more considerate. I consider myself lucky for being able to get out of the Christian lifestyle, as most people will not be able to. They are too far-gone in their brainwashing and so desperately need more comfortable answers when it comes to death, purpose, etc. My husband was raised strictly Mormon and was able to get out of that on his own; it all comes down to the courage to THINK for yourself and question/analyze everything.
As for having "proof" that god does not exist, no, you can not 100% prove that, but it is akin to my saying that there is an invisible three-headed purple dragon in my garage. You cannot prove that there isn't! That may sound silly, but it's true. As far as I'm concerned, the possibility for god is virtually non-existent so it's understandable why one would just round that figure down to zero. If the Christian god actually did exist, I would want nothing to do with him based on the Bible.
The scientific explanations for the universe are abundant. But Christians will always have their ridiculous excuses as to why the evidence isn't good enough. It's all from the devil, they'll say, or you just got to have "faith" and leave it at that.
No one will change on this matter unless they personally have the desire to. That is to say it has to be in the fundamental nature/personality of a religious person to value deep contemplation and have the courage to admit that everything they know may be wrong.
As for the http://www.godisimaginary.com/
link, I'm skeptical as to if visitors did anything more than skim it. Even if it's not written by Richard Dawkins, it brings up some very good points, even if you don't like it's style. The only reason I suggested it is because it presents its info in a much easier style than other sources. I would suggest that if that is not good enough, talk with your intelligent atheist friends in person and read actual books by Dawkins, Hitchens, and Harris on the subject (try the library if you don't want to pay for 'em). http://exchristian.net/
is another good source.