First, we'd have to see the reasoning from the Bible's tribal deity to Anselm's God. I don't see it. In fact the biblical evidence is overwhelmingly against Anselm's God being the Bible's God. To the degree someone agrees with this assessment of the Bible then to that same degree the scale of the universe undercuts the belief in the tribal deity. It does so on a continuum, by degrees.
Let's say Anselm's God exists despite the Bible, that there exists an omniscient, omnipotent, omnipresent God anyway, who represents the Christian God despite that biblical evidence. Then what? At that point we'd have to look into the probability that such a deity can be a person, that he can exist without a body, that he can know what time it is in all parts of the universe, and that he can be everywhere an atom can be found. None of these things seem probable either. To the degree someone agrees with this assessment of Anselm's God then to that same degree the scale of the universe undercuts the belief in Anselm's God. It does so on a continuum, by degrees.
But even if these insoluble problems can be solved there are two additional concerns. The first concern has to do with why Anselm's God should care about one pale blue dot in the universe with one kind of species in it. If the Gospels and Paul's writings are to be believed then why would God be so concerned about one species of life on one pale blue dot enough to die for our sins so we could be in heaven? And why are our so-called sins so egregious to this God such that they will send non-believers to an everlasting punishment, when it appears no other life on our planet or in the universe faces this same threat? These things don't seem probable either, since we don't see any evidence that Anselm's God cares for anything given natural and morally caused suffering in the world. To the degree someone agrees with this assessment of Anselm's God then to that same degree the scale of the universe undercuts the belief in Anselm's God. It does so on a continuum, by degrees.
The second concern has to do with the need for Anselm's God to create a universe on the scale we find. If this universe was created for the purpose of human life and the central redemptive act took place here, then the rest of the universe and life itself seems unnecessary at best. And if this universe is only a temporary testing ground for the heavenly reality, which is more important and everlasting, then it seems like a lot of wasted energy even if an omnipotent God exists. It doesn't seem probable that Anselm's God did this since he could have done anything else, even creating a flat earth and hanging stars in the sky, which would be just a few miles above the clouds as the ancients believed. It doesn't seem probable such a God would create the universe on such a large scale when we consider the skepticism it has produced in the minds of scientifically literate people either. To the degree someone agrees with this assessment of Anselm's God then to that same degree the scale of the universe undercuts the belief in Anselm's God. It does so on a continuum, by degrees.
Now, what if we combine these objections against Anselm's God? Let's say we don't see the Bible as supporting such a deity, nor do we see how such a deity can be a person, that he can exist without a body, that he can know what time it is in all parts of the universe, and that he can be everywhere there is an atom. And let's also say we don't see any evidence Anselm's God cares for anything given natural and morally caused suffering in the world, nor that such a God would create such a huge universe knowing it would produce the very kind of scientific skepticism of his existence that has resulted. And let's say these are overriding factors to quite a large degree. Then the scale of the universe does indeed undercut Anselm's God in a cumulative fashion by degree. For the alternative hypothesis, that Anselm's God made the earth as a flat disk with the stars hung in the sky just a few miles above the clouds, would answer all of these objections by degree.
One might think of it this way. Take for instance the existence of witchcraft. Technically speaking, we cannot conclusively prove that a Devil or his demons don’t exist, or that witches cannot work their magic. There just isn’t any evidence that they do. Furthermore, with the advancement of science, supernatural explanations for any given event in our lives become unnecessary and superfluous. A Devil empowered witch may have caused a particular illness by her spell. But what best explains why we can usually trace the illness to some undercooked food that was eaten, as an example? And what best explains why the right medicine always cures the illness? If an illness was caused by the spell of a witch there is no reason to think we could find a natural cause for it. Nor is there a reason to think the right medicine could always overcome the power of the spell by curing it either.
Technically speaking we cannot say the scale of the universe proves Anselm's deity does not exist either. But with these additional concerns the fact of the scale of the universe does lead us to think such a deity is an unnecessary hypothesis indistinguishable from the non-existence of such a God.
Now, if Lowder is arguing that the scale of the universe all by itself, without any other concerns, does not lead us to conclude as I do, then such an argument fails to take into consideration that we always assess arguments based on our background knowledge. He's arguing in a vacuum unrelated to how we actually evaluate arguments of any kind.