Assume that all reality is internal. Now, there are definitely things that can be solid rules of that internal reality. It is called scientific method. No matter how many imaginary Bunsen burners you conjure up in your internal reality, they will always and ever burn a green flame if you introduce copper to their flame. Always.

And no matter how you try to warp your internal reality with prayer and supplication, the monthly mortgage payment is going to show up each month and failure to pay it will have the same results whether you believe in god or not.

There is an internal reality that does not obey the physical laws of nature where god does exist and does bend the laws of physics. It is called psychosis.