Which preposition to use with mohammedanism

in Occurrences 7%

In 1880 he published his first important work Het Mekkaansch Feest, having resolved to devote himself entirely to the study of Mohammedanism in its widest aspects.

to Occurrences 1%

Suppose that the victories of the Saracens had extended over Europe, as well as Asia and Africa,had not been arrested by Charles Martel,would Carlyle then have preferred Mohammedanism to the Christianity of degenerate nations?

Which preposition to use with  mohammedanism