What’s the difference between believing in a god and believing that dark matter exists?

Bumsworth asked:


…and can you be agnostic about both? “Clusters of galaxies would fly apart unless they were held together by gravitational attraction. The mass required is considerably greater than the mass of all the galaxies… It follows therefore that there must be extra dark matter present in clusters of galaxies outside of the galaxies we see” Stephen Hawking.

Why does it follow?

Why must there be something else which we can not identify to make a theory valid? Could it not be something is missing from the theory rather than an “mysterious” substance that essentially requires belief in the same way that people believe in a God?….by the way any people championing a particular religion in an answer will not be considered for points
“Belief in dark matter” is a matter of logical conclusion based on scientific observation.”

I understand that science can be unemotional but how can anyone conclude anything logically when something is not observable? Surely the question of a creator/something beyond this universe can also be unemotional too, a genuine curiousity. Science tends to stop at the observable universe, understandably. And if scientists accept that there is matter we can’t detect IN this universe isn’t it fair to ask whether something we can’t detect lies beyond the universe? If science stops before asking that then fine. But it seems wrong to me to you use science to “prove” there is nothing beyond.
I don’t know if there is a god or not but I lean towards there being something beyond our physical universe where maybe our physical laws don’t apply. For me this is not a security blanket because if there IS nothing after this I’ll never know, will I?- what’s to lose? And I don’t lean towards there being something beyond for rules to govern my life. Nor do I live this life for what may follow.