You seam to have a very rosy picture of the Ottoman empire.Without going into too much detail, most historians would agree that it was an aggressive expansionist empire with intolerance to non-islamic sects.
"The terrorists you see today would become terrorists in the name of Christ just as well." - This is patently absurd, at least in this century, and a horrendously apologist argument.
I would recommend reading several key articles illustrating the Saudi Wahabi link to ISIS and how its clear that this is an intrinsically Islamist problem: eg.
http://www.newstatesman.com/world-affairs/2014/11/wahhabism-...
Also, I'd advise reading Sam Harris's "Sleepwalking Toward Armageddon"
http://www.samharris.org/blog/item/sleepwalking-toward-armag...