Answer

Hello M’,
I understood that you are asking about killing in Jewish law (such as executing Sabbath violators). I do not know what “midst” means here, and I hope I understood the question correctly.
 
There are several important differences from ISIS, and I will mention two here:
1. A religion or society is not judged only by its declarations, but also by its actions and by the implementation of its theoretical Jewish law. In practice, offenders were almost never executed (a Sanhedrin that executed once in seventy years was called destructive). In practice, the sages bypassed these halakhic instructions (whether you accept their interpretation as the text’s original intent or whether you think they circumvented it. Bottom line, they did not execute). There can be very cruel instructions, but in practice the society does not actually carry them out. For example, the law of the stubborn and rebellious son never was and never will be.
2. But even on the theoretical halakhic level, Jewish law itself does not instruct people to kill just like that. After all, one does not execute someone who acted under compulsion or someone who was not properly warned. A Sabbath violator is executed only if he is warned by two witnesses and accepts the warning upon himself (which also includes the punishment he is expected to receive) and the law. An unbeliever or idol worshipper is not executed if he is under compulsion (and even if he is compelled in his beliefs, meaning he thinks that this is the correct way to act, and truly believes in his idol). ISIS simply murders everyone who is not like them, and of course they also abuse, rape, and rob. None of this exists in Jewish law.
If you ask my opinion, when rule by Jewish law returns they will not execute anyone. In practice, that is what will happen, in my opinion. The question of how this will be anchored halakhically is secondary. Rabbi Abraham Isaac Kook writes that even sacrifices will not be brought from animals, but only from plant life.