If that's the case, you'll be able to provide evidence for it.
That doesn't strike me as tremendously difficult.
Firstly, we only know of such a thing as the physical realm - anybody who thinks there's anything else apart from the physical realm is of course perfectly free to provide what they think of as their evidence for it coupled with their methodology as to how this thing is allegedly known and claims/assertions about it evaluated. This has been asked for so many, many, many times with constant evasion from the acolytes of such a worldview that I won't be holding my breath, but the floor remains theirs.
Secondly, morality is a property or feature - a behaviour - of a certain class (a very, very, very small class, actually) of physical beings who operate according to physical laws. Whatever physical creatures do is controlled by the physical realm - if you think otherwise, the first point above applies.