A.T. Robertson Commentary John 7:41

"Others said, This is the Christ. But some said, What, doth the Christ come out of Galilee?" — John 7:41 (ASV)

This is the Christ (ουτος εστιν ο Χριστος). These went further and dared to call Jesus the Messiah and not merely the prophet who might not be the Messiah. They said it openly.

What (γαρ). These denied that Jesus was the Messiah and gave as their reason (γαρ, for) the fact that he came from Galilee. The use of μη expects a negative answer.