Regarding these 13 principles I prefaced some remarks on the parent page here
The first of the Rambam’s thirteen principles is about the existence of G-d. The Rambam writes, and I paraphrase, that the first fundamental is to believe in the existence of G-d. That there exists an entity complete and perfect in all possible aspects of perfection.
He is the cause of all existence for each creature and aspect of creation that exists. And the continued existence of every creature and every thing comes from Him.
If we were to imagine that G-d does not exist, then this would imply that nothing exists, because everything in creation gets its existence and continuity from G-d.
And the opposite, if we were to imagine that nothing in the creation existed, only G-d, that would not affect His existence, and it would not diminish it. And the unity and the ruler-ship and all the other aspects about G-d which are His alone, they are not dependent on anything or anyone else. Even if nothing else existed that would not change G-d at all.
Everything in existence is dependent on G-d for its continued existence, and G-d is not dependent on anyone or anything.
The Rambam writes that this obligation of belief is included in what the Torah says in the first of the Ten Commandments “I am the L-rd your G-d”.
Other Principles Regarding G-d:
#2 The Unity of G-d
#3 The Non-Corporeality of G-d
#4 The Eternity of G-d
#5 Only G-d Should Be Worshiped
