Yes, I realize it wasn't a scientific term. However after reading "the God delusion" I would have to say that when we speak of scientific philosophy, or scientifically we know that God only exists in the minds of the believers (as a concept, like a circle only exists as a concept).
In fact, as many God's exists as their are believers of IT, if you think about it with purity. Because each molecule in each brain is differe, there can be no true agreement on a concept of God within the the bounds of Christianity, or any other nity. This is plainly demonstrated through the multiplicated denominations, sects, non-denominations in the USA alone.
Just something to think about.