The prohibition of minarets does not have anything to do with religious freedom. You can build as many mosques as you want and you are free to pray to anyone you like. It's only the minarets (the towers on top of the mosques) that most swiss people dislike because they just don't fit in the landscape. Of course, this prohibition is an overreaction (there are only a handful of minarets already and building restrictions are strict in general), but I can understand that people think that "Heidiland" isn't supposed to look like ... e.g. Istanbul.