Why do the laws of physics and all the rest exist?
Are you asking why our particular laws (for instance, those of Newton) are the way they are as opposed to any alternative laws of physics,
or are you asking why any laws even exist?
The god aspect of this discussion leads me to think the latter, but I won't assume as much yet...

If nature was consistent in any other way, we would still have laws of physics. Perhaps you are asking why there is even
consistency, since laws are actually just assigned to model the unchanging properties of nature.
If so, I'd say that the root of this question is meant to unveil 'the explanation', which already concedes to the point of a cause. (To acknowledge an explanation is to acknowledge cause(s).)
To have causality, you must have a causal relationship. If A → B, A causes B. It wouldn't be a cause if A
sometimes meant the result B. Otherwise B could be the result of something else or 'random'. It wouldn't even necessarily be a correlation...
When you have universal causes leading to universal results, you can establish universal laws. Those laws, whatever they may be can be given names and understood separately as different laws of physics.
I've been meaning to ask, is that your cat?