I would be 100% willing to serve - believe in - an evil God (Designer, Creator, Maintainer of the Universe, Perfect Unity, Perfect Love, Perfect Mind), no less than I would be willing to believe in a square circle, and serve an unservable master. In other words, the question is what philosophers call an “absurdity.” The question posits as potential something that is not potential, that is impossible, and therefore could never be actual.
It’s not much difference from asking,
“Would you serve a perfect God if he were imperfect?”