neither is the believer necessarily being "arbitary".
If he is violating the rules of critical thought, he is being arbitrary. There is only one way to conform to them, and an uncountable number of ways to arbitrarily go off the reservation.
It's exactly analogous to addition, where the rules of reason are applied to addends rather than the evidence of the senses. If you want to arrive at a correct sum, there is only one set of rules that can do that - one right way to add. Any arbitrary deviation from orthodoxy here results in errors.
You are taking the role of the adder who wants his way of adding respected. If you believe in gods, you have not done so using reason. There is no evidence or sound argument that gets us to, "therefore God."
The world and it's people change, but that is not always for the better.
Maybe, but that doesn't rebut my contention that ancient moral codes aren't adequate for dealing with modern problems. Look at how badly American Christians are handling reproductive rights based in ancient values chosen to result in the greatest number of births possible, an ancient need. That was relevant when so many babies didn't make it to two years of age, so many mothers died in childbirth, so many men were killed at war, and so many of each died of infection and food poisoning.
A high rate of childbirth correlated with survival and prosperity. So, maidens were encouraged to marry at puberty, never to deny their husbands sex, not to use the rhythm method, don't be gay, and don't masturbate. With technical and social advances, we add don't divorce, don't use contraception, and don't get abortions. Today, it's the opposite, and this set of ideas has become immoral, which is the objection of American humanists. It is immoral to force the birth of an unwanted baby in this overpopulated world which now, unlike the worlds in which these ancient religions arose, respects human rights and autonomy. As the world changes, so do the choices that benefit or harm people.
God is not a finite person but the universe and all it contains arguably is.
So what? How does that rebut the statement, "A god can exist uncaused, correct? If so, that's special pleading." You're simply doing more special pleading here - invoking a double standard without justifying it.
What you have is an intuition that a god exists, and you argue to defend it, but you are forced to arbitrarily give that god special dispensation that you give nothing else, and the reasons that you offer are irrelevant. It makes no difference what God or the universe or the multiverse are. If one can exist without beginning, they all can. For you to say that the rules are different for the latter two is you being arbitrary.
meaningless words. What difference does it make whether the universe/multiverse is 13 billion years old or a trillion trillion?
You responded to, "If a god can exist uncreated, uncaused, undesigned, and without a beginning, so can a multiverse or a universe." If you wrote that, you didn't understand what was written to you. It doesn't matter whether the universe, the multiverse, or God is 13 billion years old or a trillion trillion years old or has existed without beginning for purposes of this argument. If a god can have existed eternally into the past, so can a multiverse and a universe.