God's God

[Neo-Scholastic]

More like: As far as we know, everything requires a cause. Existence might too, but we don't know, so we'll hold off saying for sure until we do.

No exactly. 'Coming into being' is a property of all physical objects. Every physical object with which we have experience has a beginning and persists and presumably ends. The coming into being of any physical object depends on something other than itself into order to begin and persist (which is just continual coming into being).

The known universe is a physical object, the same as all others. So even as a whole, the physical universe should not be treated differently than any other physical object. To do otherwise, one must start 'special pleading'. To avoid 'special pleading' you posit the existence of a non-physical thing on which all physical things, including the known universe, depend.