War isn't the way to stop this. The best way to stop this is to impose absurd, immense sanctions on every Middle East country, on the UK and the Philippines (all the most densely populated areas with the highest rates of Islamic faith followers). Sanction them so severely until they are willing to issue a mandate to all citizens that Apostacy will no longer be punishable. You have to force reform, or this will continue indefinitely. Leaving Islam to another faith, or being agnostic or atheist carries the death penalty or a mandatory tribunal hearing in which the accused will be jailed or executed.

That is step one. Force all countries with a massive influx of Muslims to reform that and overnight hundreds of millions in Islam will leave it. It will crumble the religion in a week and drop that 1.6 billion to less than a billion within a month or two. In a year to a decade, Islam will be a minority religion.

War and hate is not the answer for step one.

Step 2 should be to force yet more sanctions upon the entire middle east and cut them off from oil sale and purchasing. Stop buying their oil, they will do anything the world wants them to. The deal will be to ban Islam completely. They'll do it when Saudi oil stops flowing.

Within 5 years of doing that, you can dwindle the religion to a point where it is manageable for the rest of the world. From there on, you can keep on eye on terror groups who are now in the public eye for not adhering to the new sanctions and laws, all eyes will be on them and they will be ousted often for rewards.

Islam dies in ten years tops. Terrorism attacks drops significantly. The entire world becomes a much happier, safer place and not one bomb or bullet needs to be dropped or fired to accomplish it.