That would be a case for "god" because you weren't calling Him by name.
And 'god' with a lowercase 'g' would still need to exist as a word for when you referenced, what you believe to be, other people's fictional gods or in reference to your own, as in:
"My god is the only real god."
As opposed to:
"God (name) says unicorns exist in Psalms," not that your god's name is God anyways.