Not for the Judeo-Christian God. It doesn't matter what we, IRL, think. What matters is what the people who are considered 'experts' on the subject think. Magnus and Ahriman, the two characters in a position to know such things, both agree that there are no Gods. This is the metaphysics of the setting.
We use the term as the setting applies it. Which is apparently the JC God that is all-knowing, all-powerful, unkillable. And the Chaos Gods are none of those three things, and neither is the Emperor.