"I don't believe in God"

Many Christians argue that when a proclaimed atheist uses this phrase, they are acknowleding the presence of God and therefore are contradicting themselves - I disagree.

I use phrases like "I do not believe in aliens" and I'm sure many people have used phrases like this also. It is acknowledging the IDEA of that thing, in this case, aliens or God. The idea has a name because someone else thought it existed. I mean, what's the alternative? Saying "I dont' believe in.....?". That's silly!