Thank you Sharif for saying this. It would help if more Muslims would do likewise. Why do you suppose they aren't?
They're afraid to say it; when a few very vocal and violent thugs are added to a group of decent folk, the decent folk are quickly cowed into silence. Their silence encourages the thugs to go beyond intimidation of their own people, to outright violence against any dissenters, and more violence directed towards outsiders. The perps know their group is unhappy but deflect this by blaming outsiders for their ills, and they go on to attack people beyond their group. Meanwhile, their group remains cowed into silence. And that silence angers the outsiders who are also being victimized by the thugs. The anger results in vigilanteism at times, which in turn makes blaming outsiders and violence agaisnt them seem justifiable. It's a vicious circle.
But the circle can be broken when the people in the base group realize that they can take on the thugs and start to speak out in condemnation of them. They can clean out undesireables in their communities by standing up for what is right, instead of protecting those who are wrong.