Your conclusion doesn’t follow your premise. Even atheists who don’t hold to the multiverse theory don’t feel compelled to admit to a creator to this one provable universe. I side with John Lennox on this one. Whether we ever prove the multiverse theory or not, God is not found in scientific proofs.
The CCC#286 states “Human intelligence is surely already capable of finding a response to the question of origins. the existence of God the Creator can be known with certainty through his works, by the light of human reason, even if this knowledge is often obscured and disfigured by error.”
St Paul says “For what can be known about God is evident to them, because God made it evident to them. Ever since the creation of the world, his invisible attributes of eternal power and divinity have been able to be understood and perceived in what he has made. As a result, they have no excuse; for although they knew God they did not accord him glory as God or give him thanks. Instead, they became vain in their reasoning, and their senseless minds were darkened. While claiming to be wise, they became fools and exchanged the glory of the immortal God for the likeness of an image of mortal man or of birds or of four-legged animals or of snakes” (Romans 1: 19-23).
And "The fool says in his heart,
“There is no God.” (Psalm 14:1)
And “The heavens declare the glory of God;
the firmament proclaims the works of his hands.
Day unto day pours forth speech;
night unto night whispers knowledge.
There is no speech, no words;
their voice is not heard;
A report goes forth through all the earth,
their messages, to the ends of the world” (Psalm 19: 2-5).
St Thomas Aquinas in his summa theologica proves that the existence of God can be demonstrated by the natural light of reason through that science which is called metaphysics or first philosophy and common sense of which the denial is conceptually incoherent and inexplicable.
So, according to Holy Scripture, the teaching of the Catholic Church, and the philosophy of St Thomas Aquinas, the existence of God the creator can be known with certainty by the natural light of reason.