Are the thoughts that come to mind about the non-existence of a Creator for the universe the beginning of disbelief, and how can one get rid of them, draw closer to Allah, and achieve devotion in prayer?

Intrusive thoughts, passing notions, and doubts are pardoned and not held against a person, as long as they are not acted upon, believed in, or spoken aloud. This is based on the Prophet's (peace be upon him) saying: "Indeed, Allah has pardoned for my Ummah what they whisper to themselves, as long as they do not act upon it or speak of it."

One should turn away from contemplating the whispers of Satan and fight against them.

And Allah knows best.