To play Devil's Advocate here (yes, intentional-ish irony):
1. This rock is 4 million years old. The Bible says the world is some 10000 years old.
We're at the point where all rational people know the real age the Earth, even many Christians, although this point's validity remains. However, the bible does not actually say the Earth is 10,000 years old; if I recall, it gives no year-specific age.
2. Many of the things in the bible are scientifically impossible
3. There is no proof of a god except a old book.
True, but if you or I or anyone expects anyone else to take that point seriously, don't just SAY it. I could say there's no proof the sky is blue; that doesn't make it true, because, well, there is proof. In other words, point out that, say, there's no fossil records of giants, and there is no scientifically verifiable way of proving the existance of any afterlife.
4. Ancient People were always trying to explain things with Religion, and we are now proving them wrong.
Actually, a pretty valid point. Specificism (not a word, is it?) would help, though.
5. Christianity has constantly changed. It used to be popular that if you were a good christian, you would burn innocent woman at a stake, because they were WITCHEZ!
Again, true, but presented in a pretty tactless way.
I'm sorry if I sound like an English teacher here, but the point I'm trying to make is that if anyone's to try making any point here, please do so in a well thought-out manner. Screaming your beliefs in list form does not a good argument make. Zarkanthesmasher's right; almost all Atheists I see act in a condescending and insulting manner when presenting their views, and it disappoints me.