A valid argument extracts the implications of its premises. So unless one of my premises asserts God's existence - and none do - the argument is not question begging.
To put it another way, you can't accuse an argument of begging the question just if its premises entail its conclusion, for that would make all valid arguments question begging and thus would render the charge vacuous.
My first premise says
1. If there are laws of Reason, then there is a mind whose laws they are — Bartricks
Subsequent premises - each independently supported - entail that the mind in question exists and is God. So it certainly doesn't beg the question.
I also provided an argument in support of it. First, imperatives of Reason, norms of Reason, call them what you will, are imperatives - directives, instructions, prescriptions. That's why they're called 'imperatives' and why they're called 'norms' and why the word 'reason' that can sometimes be used as a substitute for them is called a 'normative' reason. That isn't controversial.
Then there's my claim that imperatives need a mind to issue them. That's a self-evident truth. It's hard to argue for a claim as self-evidently true as that one, for one almost invariably ends up appealing to other claims that are less self-evidently true than the claim one is trying to argue for (which is why Aristotle advised against it). But I illustrated its self-evidence by pointing out that if I was discovered to be a bot, none of this would be a real communication, precisely because these words would not be expressing the desires or thoughts of a mind.
So, my first premise does not beg any questions. Its truth is entailed by truths that are beyond dispute. And, in conjunction with the other premises - which have the same status, I think - it entails that God exists.
If you believe it already, then there’s no need to prove it, but if you’re determined not to believe it, then the argument is not going to be persuasive; someone who wishes not to believe it will always find a way to justify themselves. — Wayfarer
That's false. I believe in God on the basis of the argument. I didn't believe in God before I reflected on the argument. I did afterwards, and I did precisely because I could not find any grounds for a reasonable doubt about any of its premises.
Those who think arguments are impotent to persuade people reveal, I think, something about themselves: namely that it is they themselves who have decided what's true in advance and are not interested in following Reason unless Reason tells them what they want to hear. They then tar everyone else with the same brush so that they do not have to feel too guilty about their self-indulgence. But we're not all like that.
But anyway, the fact is it is also irrelevant. A proof is a proof. It doesn't have to persuade. What's persuasive to people is a function of the psychologies of people, not a function of what's true.
Why the upper case R - it is to indicate that it is now being used to refer to the source of the imperatives, including the source of all reasons to do and believe things (the latter having a lower case r)