Shaykh Muḥammad ibn Sāliḥ al-ʿUthaymīn:
When the issue of the brothers became apparent, those who acted without wisdom, the image of Islam became ugly in the eyes of the westerners and other than them. By this I refer to those who throw explosives in crowds of people, claiming it is from Jihād in the path of Allah ﷻ.
In reality they have insulted Islam and its people much more than helped it. What did these people achieve? I ask you “Did the non-Muslims turn to Islam or were they driven away from it?”
They were driven away from it!
The Muslims even try to cover their faces so (the people) do not associate them to this frightening and shocking group. Islam is free from them! ISLAM is free from them!
Even after Jihād was revealed, never did the companions go to the non-Muslim communities and kill them, ever! Except in a Jihād which had a flag (legislation) from the leader in charge, who had the ability to carry it out.
As for this terrorism, by Allah it is problematic for the Muslims, I swear by Allah ﷻ.
We can see the result and there is never a good outcome. Rather in contrary, it ruins the reputation (of Islam). If we acted upon wisdom, rectified and feared Allah ﷻ within ourselves initially and then rectified others in the legislated way, it would have produced better results.