Why are religious people seemingly unable to hypothesise about a universe without God? I know many devoutly religious people despite being totally atheist myself. I have occasionally discussed their beliefs and their religion with them, always respectfully. I am able to hypothesise scenarios assuming their beliefs are correct. However, when I ask them to consider my point of view, they seem unable to do so, because to them it doesn't make sense that God doesn't exist, or whatever else is said in their religious texts.

I view it like visiting their home. I can visit them and enjoy their hospitality and they enjoy showing me around their home but I don't want to move in with them (convert to their religion). If I invite them to visit my home (hypothesise a universe without God), they always refuse. I'm not suggesting that they move in with me (become an atheist), and in fact, I don't care whether they do or not, and I don't even have any expectation that they would.

It seems as though atheism is so uncomfortable to them that they reject it without examining it except in a very general and distant way. The strange thing is, that they all view me as a good person despite me not sharing their beliefs.

Why is it so difficult for them to discuss atheist principles when I have no trouble discussing their religion with them? In fact, I find religions fascinating in the same way that I find people living in other countries fascinating.
To quote the great Aldous Huxley :

How shall we define a god? Expressed in psychological terms (which are
primary-there is no getting behind them) a god is something that gives
us the peculiar kind of feeling which Professor Otto has called
“numinous”. Numinous feelings are the original god-stuff from which
the theory-making mind extracts the individualised gods of the
pantheon.
— Aldous Huxley

Even &quot;the Hitch&quot; acknowledged the Numinous :

I’m a materialist…yet there is something beyond the material, or not
entirely consistent with it, what you could call the Numinous, the
Transcendent, or at its best the Ecstatic. […] It’s in certain music,
landscape, certain creative work, without this we really would merely
be primates. It’s important to appreciate the finesse of that, and
religion has done a very good job of enshrining it in music and
architecture.
— Christopher Hitchens

However, he also pointed out this :

I think everybody has had the experience at some point when they feel
that there’s more to life than just matter. But I think it’s very
important to keep that under control and not to hand it over to be
exploited by […] those who think that God has given them instructions.
— Christopher Hitchens

This is the cause of the divide between Theists and Atheists. Both experience the Numinous more or less the same way, but Atheists look for explanations in science whereas Theists look for ancient texts they believe to be divine revelations.
So why do some look for explanations in science whereas others look for explanations in ancient texts? It's a matter of cognitive style. More in particular, in depends on your empathy and systemizing quotients.
Extreme systemizers are not very likely to follow &quot;their gut&quot; (they may even be incapable of experiencing intuition). Because of that, they're also less likely to follow any kind of external authority. Their systemizing nature requires a rigidly consistent logical framework to make sense of things, which they often find only in science.
In contrast, extreme empathizers are more likely to follow &quot;their gut&quot;, and also more likely to follow any kind of authority (including ancient religious texts). They tend to feel a lot more comfortable with experiencing cognitive dissonance and logical frameworks lacking consistence, which is common for religion.
Still, I believe the gap between Theism and Atheism largely relies on purely semantic differences with respect to how both approach the Numinous. I address this in greater detail in my article The Atheistic approach to God… or how to bridge the gap between Atheists and Theists.

Edit :
With respect to extreme empathizers being more comfortable experiencing cognitive dissonance, I'm refering to cognitive dissonance at the level of belief. It's more important to them that their emotions correspond with their beliefs than that their set of beliefs as a whole is a consistent set.
In contrast, extreme systemizers care mostly about their set of beliefs forming a consistent framework.