Science isn't actually "physicalist". In fact one major theory in science, Quantum Mechanics, would probably challenge physicalism since quantum suggests that there will always be unknowable physical quantities regarding any given particle of matter. It also suggests that particles of matter (and light) must interact with an observer in order to exist in a state where some physical quantities can be known; else these particles exist only in an exotic state of indefinite probalistic fluctuations.

I must say though, even though quantum challenges physicalism, quantum's model of the universe truly rejects the possibility of any omniscient entity. Omniscience requires the ability to know everything about the universe and quantum suggests that this is in fact impossible; therefore a truly omniscient god would be impossible. It was for this reason that god-fearing Albert Einstein rejected quantum mechanics up until his death bed.