There are never any winners in regards to religion.
It's extremely rare for a person to alter his or her beliefs regardless of the literature (fact or fiction), events or the preaching of leaders or so called extremists.
Debating it is probably a mute point at best.
Yep. As I have pointed out before, people's faith is based (in most cases) on what their parents taught them. So a believer's faith is based on birth, not logic or truth.
So, these people running around killing people in the name of some god would not be doing so if they had simply been born into a family with different beliefs.
You see it in other aspects of life. What sort of car you drive, where you live, who you follow in sport, who you vote for. While these are not as immovable as religious belief, it shows that it's a common human trait.
Further to that, once a person has had a way of thinking or belief indoctrinated into them at birth, it's very, very difficult to move that, to change belief. It usually takes a traumatic event, such as war, death, sickness, or some other trauma, such as child abuse, rape or other physical abuse.
If discrepancies pop up, they are excused or explained away, sometimes with very complex reasoning.
An example of that would be when something written in the Quran or the Bible is in conflict with a person's faith. No matter what you put forward as evidence, it's explained away. For example, the jihad in the Quran is used to justify terrorist attacks by some, but for those who are against such violence, the offending passages are softened or reinterpreted.
Same with the Bible. Should gay marriage be allowed? Well, how about going to the core of the issue. Should homosexuality be accepted? Not according to the bible. It's black and white. But in our society that is all explained away or ignored. Then there is the other extreme where you have people shooting up abortion clinics.
I'm talking here about people with a specific religious belief, not your average non religious westerner who has no need to justify their views based on a religion they don't follow.
Are these terrorist attacks based on Islamic belief? Yes. Do all Muslim follow the same way of thinking? No. So it is, essentially, a matter of theological interpretation. Pity people have to die for that.