When speaking of an all knowning God grammatically you should use a capital G
Nope--ask the writer. It is absolutely, grammatically correct to write:
"reasoning that there is a god."
The indefininte article (a) indicates that this is one of a larger number gods.
Lower case 'g' would also be proper when using a definite article, as in pointing out a specific god.
The god of the Israelites condoned genocide.
Now, if you were to use the term god as a proper name, then it would be proper to capitalize it.
God approved of rapists buying their victims from their fathers.
But watch how we can mix such:
God is a god that demands adulterers be stoned.
I'm happy I could clear that up for you.
NC