FOUNDATION of ONTOLOGICAL REALITY
Something obviously exists. The question is why or how something exists. Either something came from nothing, or something is eternal. It is not possible that something came from nothing. Therefore at least one thing is eternal.
It cannot be known how many things are eternal, nor if one is Supreme.
Powerful beings exist. Therefore a most powerful being exists.
The most powerful being may not necessarily be more powerful than a coalition of other beings.
Therefore, from the existence of power, it cannot be known if a Supreme Being exists or not.
Examples of possibly homogeneous things: time, space
It is not possible that anything can come from something homogeneous except more of the same homogeneous substance.
Most of those things come from something else.
Therefore that from which those multiple things come must contain parts.
Therefore at least one eternal thing must contain parts.
An eternal thing may contain eternal and temporal parts.
or temporal things were created by something eternal,
or some temporal things are part of something eternal,
It is not possible to create power without first having power.
Therefore power must be an eternal part of the original Creator.
Only something eternal can have an eternal part.
Therefore the original Creator must be eternal.
Humans can create machines which are greater than humans in any quantifiable attribute. Therefore it is possible that a Supreme Being could create beings which are greater than Himself in any quantifiable attribute, possibly even including power, though He would no longer be supreme after having done so.
Relative to this (Big Bang) universe a most powerful being exists, which may be unrelated to the most powerful of eternal beings. I see no way to know, or reason to care, if the most powewrful Being relative to this universe is Supreme (even relative to this universe).