Before science took over there was a big invisible guy in the sky who could do anything. He created himself from nothing, but nothing else can be created from nothing because I say so.
God is not described as being invisible. The trinity describes God as Father, Son and Holy spirit. Scripture describes God the father as having a face, as having the likeness of man, as having a breath and as walking with Adam. The Son has 30 plus year recorded history on earth. The Holy Spirit has been observed as a flame. God is described as having from and substance.
who could do anything.
Except sin.
He created himself from nothing,
God never claims he created himself. He says "I am". He says he is the alpha and omega. The beginning and the end.
but nothing else can be created from nothing because I say so.
The actual term is ex-nihilo. One of the mysteries of theology is the meaning of "And the earth was without form, and void; and darkness [was] upon the face of the deep." Is this truly nothing? Saying yes solves a number of theological issues and brings many other characteristics of God into harmony. However, can we read that far into the passage? Perhaps. Most do. Myself included.