Exotheology is like thinking about what we would believe if we met aliens from another planet. Just like how we have religions like Christianity and Islam here on Earth, the idea is that there might be religions on other planets that have different beliefs about things like God, the Universe, and what happens after we die.
It's kind of like how we have different languages here on Earth - people in one country might speak Spanish while people in another country speak Mandarin. Similarly, aliens from another planet might have different beliefs about how the Universe was created or what happens after we die.
Scientists who study exotheology try to imagine what these alien religions might be like based on what we know about science and how humans on Earth think about religion. They think about questions like: Do aliens have souls? Do they believe in a higher power or multiple gods? How do they explain things like good and evil?
It's important to note that we haven't actually found any evidence of extraterrestrial life yet, so exotheology is still mostly just a theory. But it's interesting to think about what the world might be like if we did find life on other planets and what it might teach us about our own belief systems.