It doesn't have to be all or nothing.
To be equal, we can allow churches to ding the bell once a week on sunday, and allow mosques to recite call to prayer once a week on friday.
If you live in a country where Christianity is the state religion, you could just disallow the call to prayer on account of the fact it is not Christian. (One advantage of a state religion is that you can do stuff like this. Of course, you have to be careful not to take it too far - condemning unbelievers to death might be a bit much, for example.)