Extremism, adhering to old "understandings" that are no longer applicable can be an issue. As can intolerance (especially extreme intolerance) of others' viewpoints. But not religion per se, which is at root simply an belief/understanding or spiritual matters that is held held by a large group.
Naturally any such group and it's authorities can abuse power, as can those unable to understand but who just take things literally; but that isn't the same as religion being sick.
One might as well level the same criticism at atheism the next time an atheist decides they can do what they like to others for there is no reason to believe in a general frame of good & bad, or whatever. If there is responsibility it is with the individual who misunderstood.