"परमेश्वर के नियम सभी पर" is an incomplete sentence, so it cannot mean "God Rules Over All." Only a complete sentence and context can tell what "परमेश्वर के नियम सभी पर" can mean for whatever you're concerned with. "परमेश्वर के नियम सभी पर" means "the rules of God on all," which is not a complete sentence.
The phrase could literally be understood as, "God's rules [are] upon all" which I would have expected as "परमेश्वर का नियम सभी पर" (God's rule [is] upon all). One could take the meaning as that "God's rules are over all" and "Everyone should abide by God's rules". So, it does not clearly give one meaning.
As for this being an incomplete sentence, one does have pithy, proverbial sayings where the verb is understood, e.g
It sounds like an incomplete sentence to me too, and I agree that it's probably enough of a sentence, even if it is incomplete, to at least get the gist across. If you'd like a completion of your sentence, you could do something like this:
परमेश्वर के नियम सभी पर लागू होते हैं।
parameshvar ke niyam sabhii par laaguu hote haiN.
God's rules apply to everyone.
But there are many other ways of expressing similar thoughts. If you want a different way, perhaps you could do something like this:
हम सब खुदा के इख्तियार में हैं।
ham sab khudaa ke ikhtiyaar meN haiN.
We are all in God's jurisdiction.
You could also decide to use the spellings ख़ुदा (xudaa) and इख़्तियार (ixtiyaar). Others may have other suggestions!