o yeah, why make up and pass laws if they cant be practiced? yeah why indeed? you see religion is a force that compels people to form to the laws of God to lead a peaceful life. That however is not guaranteed by professing the Shahada alone. The utterance of those few words does not automatically lead to a harmonious life. You would have to act accordingly as well.
Mavericks are always there and give a low life unemployed guy something to live up to, he would do anything. Terrorism is not however unique to muslims alone and nationalist and revolutionary forces all around the world have readily engaged in one form or the other. Since Islam lays much stress on the unity and freedom of the Ummah in specific its not much of a big suprise that terrorism is adopted by some to fight the enroaching West. Fighting for your homeland and to claim whats rightfully your is indeed a duty for every muslim, but of course not how you see today. Terrorism is the easy way out for them and they fail to appreciate the real situation. The terrorist find their motivation to fight from religion, but the ways are completely different.