It's generally called pantheism, although there has been dispute [1] that Spinoza's account was truly pantheism. Similar ideas exist in Hindu philosophy, and some argue the analogy is deep [2].

1: https://en.wikipedia.org/wiki/Panentheism

2: https://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article=454...

Check out "cosmological argument"

https://en.m.wikipedia.org/wiki/Cosmological_argument

To me it seems equivalent to the "first cause" argument of Thomas Aquinas.

You can also check out Aristotle's primum movens (prime mover)

https://en.wikipedia.org/wiki/Unmoved_mover

Deism?