I don't know what saints may have ever mocked God, but what I do know is that not one of them ever mocked God by denying the flatness of the Earth. To deny the flatness of the Earth is in no way, shape, or form to mock God! If you don't agree I would ask you to provide any exact references/sources/quotes you may have for any saints' clear and unambiguous assertions that the Earth is flat.
Church father
Lactentius in the Divine institutes, Chapter 24 :
they thought that the world is round like a ball, and
they fancied that the heaven revolves in accordance with the motion of
the heavenly bodies; and thus that the stars and sun, when they have
set, by the very rapidity of the motion of the world are borne back to
the east. Therefore they both constructed brazen orbs, as though after
the figure of the world, and engraved upon them certain monstrous
images, which they said were constellations.
....I am at a loss what to say respecting those who, when they have
once erred,
consistently persevere in their folly, and defend one vain
thing by another; but that I sometimes imagine that they either discuss
philosophy for the sake of a jest, or purposely and knowingly undertake
to defend falsehoods, as if to exercise or display their talents on
false subjects.
St. John Chrysostom Commentary on the Hebrews 8:1“Where are those who say that the heaven is in motion? Where are those who think it is spherical? For both these opinions are here swept away.”
Quoted by Cosmas.
St. Jerome, Commentary on IsaiahGod "[had] established the great mass of the land and had gathered it together above the seas and rivers, so that the heaviest element [earth] hangs over the lighter weight waters by the will of God, who like a king sits above the circle of the earth. There are some who assert that this mass is like a point and
globe...What, then, will the land be over ...?"
Original latin
here