If you're actually Jesus, how come you can only walk on gravy, not water?

( TFD is sporting this season's finest necropants, Thu 3 Mar 2011, 14:26, archived)

i only walk on gravy made by peoples' mums.
that way i can just walk across the lumps like stepping stones
( manolith hooray for me, Thu 3 Mar 2011, 14:34, archived)