Why is Islam popular in prison?

(There are moderate Muslims.  This particular post, however, is not about them.)

Bookworm writes that conversion to a religion "looks good" in prison (I presume that means that parole boards like it).  But, there is more:

Further, as my cousin, the prison pastor, says:

It is not a contradiction to be a Muslim and a murderer, even a mass murderer. That is one reason why criminals “convert” to Islam in prison. They don’t convert at all; they similarly remain the angry judgmental vicious beings they always have been. They simply add “religious” diatribes to their personal invective. Islam does not inspire a crisis of conscience, just inspirations to outrage.

This video (hat tip: GayPatriot) explains three key facts about Islam that every Westerner should know:

PREVIOUSLY on subjects related to Islam:
•Obama and the stifling of dissent
•The philosophy that shall not be named
•Turkey wants to try Pope for insulting Islam