You seem to assume three things:
- that religious people are mostly fanatics,
- that fanaticism is inherently bad,
- that the alternative—secular leftism—is not fanatical.
You can easily see that none of the above assumptions comes close to truth.
Many religious people are quiet people and good neighbors. Monotheism is inherently intolerant, but that intolerance is hardly important in practice.
Fanaticism is a charged word. How about, “motivation”? Or, “people with a strong sense of values”? Weren’t the Americans fanatical when they fought the Nazis over a very abstract thing, freedom?
The secular left fanatically adheres to many dogmas which are less defensible than aboriginal theology. Democracy, especially democracy for all nations, is one such dogma. Democracy was meant to be a system for governing daily affairs (not even the core values) of small culturally homogenous and affluent city-states, not huge heterogeneous countries. The Bible flatly argues against democracy when it prohibits following the majority to evil.
Religious people are prone to violence? How many soldiers in WWII, Vietnam, or Iraq were religious? People are naturally violent, and violence drips through many lines, but religious violence is nothing compared to that of secular regimes.
You suggest that the religious people are unable to compromise. Is compromising inherently good? You compromised in WWI but not in WWII. You compromised on gay marriage, and what possibly prevents you from legalizing polygamy and zoophilia?
On other hand, religious people compromise a lot. Religious Jews of the second century peacefully coexisted with Jewish Christians. Modern Orthodox rabbis have accommodated Christian icon worship in Israel. Jewish religious law is, in fact, very flexible, and we can see how the rabbis, for better or for worse, bent the commandments to practice. Rabbis don’t press for the extreme goal of establishing the Land of Israel from the Nile to Euphrates. If there’s one complaint to be made against the rabbis, it is that they are actually on the left. They want to look respectable with sponsors and secular friends, and are thus moderate. Most rabbis criticize zealous Jewish nationalists, and argue for modernity, democracy, and tolerance at the expense of the commandments. On other hand, only about half of the most radical right are religious. Right and religious are not the same, or even significantly correlated.
I agree with you that not a great difference, in practical terms, exists between Jewish and Muslim radicals. I respect Muslim radicals, however, as courageous fighters.
When you speak of the left, you apparently mean secular Zionists rather than the corrupt and morally decomposed socialist crowd which absurdly calls for collaboration with the enemy. Whig liberals stood for and fought for their values. Zhabotinsky, a Zionist par excellence, was secular, yet he is considered ultra-right. There’s confusion about the terms.
Religious wars are not wars for nothing. Few wars in recent history were economically motivated, and still fewer wars throughout history were economically viable.