I had assumed in large part the "one" God is a vague, monotheistic idea that applies to the creator of the universe who probably doesn't actively interfere with his/her/its creation, and further details are not necessary. It's just a general acknowledgement to any who adhere to a monotheistic point of view, and the so-called God is that one - the one - whatever your personal beliefs may be that might make that one God somehow different from another person's or culture's one God, you can believe those, but not insist on it of others, and nor can they insist their POV is the one and only correct version of the one God. It's all the same God - the one God, the creator of the universe.
If one does not adhere to monotheism in general, you might ask which God, but you'd be told it is just a general reference to a monotheistic belief of a supreme creator of the universe, whoever or whatever that may be.
If one does adhere to monotheism, there is no reason to ask which God.
If one adheres to atheism, as long as the culture is tolerant and not insistent one accept and adopt their POV, or else, they should just let it slide without much comment since few atheists really feel the need to make converts, and if they aren't hurting anyone by their beliefs, they should be allowed to believe what they want, pretty much under the philosophy of the Golden Rule - that is, you wouldn't want somebody forcing their religious beliefs on you, so you shouldn't try to force yours on others.
From all that, I suspect Kirk is a monotheist, and he feels no reason to ask which one, or insist on a particular one.
I'd like to assume Earth's major monotheistic religions adopted that policy by Kirk's time, and while they may hold certain attributes to their God, and which may be different in some regards to another monotheist's God's attributes, they are both tolerant of one another's differences and do not seek to impose their religious POV on others. Christianity, Judaism, Islam, and maybe other monotheistic beliefs may all happily acknowledge this general belief in - the one - without fighting about it.
One.
Are you One, Herbert?
I am not Herbert.
He's not Herbert. We Reach.
Oh, O.K., they probably weren't talking about monotheism there.
