The problem is that countries are destabilised because of colonialism and foreign involvement because of oil, dictators take over, people rebel, the dictators hire extremist groups to put them down, but these groups end up becoming huge terrorist groups. This is how Al-Qaeda and ISIS were formed. Muslims across the world have condemned these acts of terrorism, and they consider the terrorists not proper members of the religion. The culprit is weak governments due to colonialism, not Islam. If America were destabilised, you would get groups like ISIS, but Christian, and the Islamic world, Asia and Africa would look down on them, branding Christianity as a religion of violence, whilst the US government and wider Christendom condemned these extremist groups, and you would either join Christian ISIS or be angry at the Muslims that they think all Christians are violent