Stand outside several churches, and several synagogues, at the end of services.
Watch the people come out. How are they behaving? What are their facial expressions and body language indicating?
OK. Did you find that generally people leaving services were content, animated, happy, talkative, and gregarious?
Now stand outside several mosques and repeat this study. Out they straggle, subdued, angry, stressed.
What does this tell you?
Every one looks like he wants to tear me apart with his bare hands.
There is a very large mosque / muslim center in my hometown where that is indeed the case. Bearded men, wearing surplus army jackets, glowering at me, the infidel.
Counterexample: the small local Amadiyya mosque, which seems to attract agreeable people from the looks of them (though I don't know what their imam says inside).
Radical islam is an insane death cult, and "moderate islam" is its trojan horse.