Is anyone denying that the Quran and the Hadith appeal more to violence in its adherents than the Bible and the Old Testament?
The pacifist Jesus aside the Jewish Torah and Talmud are probably the most bloody of the holy books, surpassing even the Quran, but there's some fundamental differences. Firstly, in Islam the life of the Prophet is held as the ideal; a bloody 7th century warlord. And not just as ideal, as maybe you could argue Abraham or Moses is to some Jews and Jesus is to Christians, but as someone whose life or opinion you should try to emulate down to even the tiniest detail, hence the Hadith tradition and hence anyone who reads the Quran as the actual word of God.
There's also major differences in the concepts of Paradise and matyrdom. But most importantly the idea of holy war that we simply don't see any reasonable number from any other religious belief, however stupid, adhere to or support like we do in the Muslim faith.
Is there a relation between action and belief? Certainly. Fortunately a majority of the world's 1.57 billion Muslims close their eyes to the incredible violence practically being not only supported but set up as a religious ideal in the scripture and pick out rituals and convenient interpretations (usually variations of the golden rule), but all statistics show a worrisome percentage, even in the West, who have some incredibly dangerous and backwards beliefs.
What I think is hard for many secular people in the west to grasp is that people actually believe these things, and that you often cannot blame it on some social issue. People like the Dáesh really believe the insanity they are preaching, it's religious fanaticism that regrettably have way too much support in the Muslim world.