Their God existed indeed and it was there in the sky for everyone to see. If you don't agree with them about their God's ability to interact with them, that's a matter of opinion. If the point is debating existence, I say their God did indeed exist, and there is evidence to back it up.
However, Cofty, you're resorting to your usual strawman fallacy here. The point of absentheism isn't asserting the existence or non-existence of deities. It simply is asserting that the only thing that we can confidently say about them - and back it up with evidence - is that they're absent. If you want to do your tired number of grandiose claims that God doesn't exist, then be prepared to provide overwhelming evidence for it. The kind of evidence you usually demand from theists.
Eden