It would be interesting to tally the death toll rung up by Marxist/socialist governments and Islamic governments over the last century, and compare that figure with the century's total dead by other than natural causes. I haven't undertaken the exercise, but am confident that such an accounting would shed much light on where humanity's real problems lie.
I regard left-liberalism and radical Islam as the two greatest philosophical threats to civilized society. The word Islam literally means submission, and Islamic doctrine divides the world into Dar al-Islam (House of Submission) and Dar al-Harb (House of War). Clearly, Islam's adherents always saw themselves at war with the rest of the world, and 14 centuries of bad behavior are there to clear up any remaining doubt.
Lately, I've been comparing the psychology of modern left-liberalism with that of Islam. The parallels are surprising - particularly in the areas of intolerance of competing views and the subjugation of non-believers. Like Muslims, leftists play for keeps. They're uninterested in reasoned debate, preferring to destroy competing views in much the same way Islam is commanded to subjugate, convert or kill infidels. Both are violent expansionist doctrines, and dhimmitude is rather difficult to distinguish from forced participation in Obamacare when you get right down to it.
I would note that despite the delusional BS of cowardly politicians, there can be no such thing as a peace loving Islamist any more than there can be peace loving Marxists/socialists. In both doctrines, adherents are commanded by their radical god to conquer and subjugate.
When your god is a violent radical, you have no choice in the matter. This fully explains the conspicuous lack of criticism of the barbaric acts of either leftists or Islamists by any followers of either.
I was delighted to discover a blog focused exclusively on the critical examination of radical Islam. It's called Citizen Warrior, and the link takes you directly to an older article that is outstanding work.