Because it is capitalised, it is true.
Well given the fact that God was capitalized that would affirm that it was the God of the Bible he was talking about.
"Do You Capitalize the Word "God"?
One of the most common questions people ask about religious words is whether to capitalize the word “god.” The name of any specific deity is capitalized just like any other name, so when “God” is used to refer to “the one God,”(in other words, in any monotheistic religion) it is capitalized. "
"Indeed, it would be rather juvenile to misspell God simply in order to insult theists. If such an atheist had so little respect for another person, why even waste the time writing to them in the first place, much less deliberately trying to hurt them at the same time? While that may actually be the case with some atheists who write the word 'god' with a lowercase 'g,' "