Thou shall not kill

I've recently been listening to Quran (audio tapes) and i heard the most interesting thing, i can't remember the text exactly and it's location but i can sure dig it up, but it meant, whoever kills one soul without the right to do so, it's as if he killed all.

I was really interested after hearing that, because, eventhough, i am a muslim, i had no idea what incredible weight was given to human life, and it really made me wonder, if such text is in the Quraan, how come no one bothered to realize that muslims don't just go around killing people, and that god has put so much restriction on taking any life regardless of whether it is muslim, christian, buddhist or whatsoever, as the phrase didn't specify muslims but said "nafs" which is "self" or "soul".

A lot of people say that if muslims see all the terror as wrong they should condemn it, and try to prevent muslims from committing such crimes, but the thing is, Why should we defend ourselves in the first place? why do you assume that those people have done such crimes in the name of God? Why do you belive the words of your politicians? eventhough they have blatantly lied to you over and over again? are muslims supposed to gather up funds to prepare documentaries and media and propaganda t try to fight back the incredible dellusions and misinformation twisted by politicians for their own interests and packaged and delivered by a media which is controlled others with other Agendas which may include the erradication of the islamic religion or just making money?

If you want to be just in your opinion and judgement of people in life, look up what islam really is about, read! and then come to the verdict of whether such acts are really motivated by Islam and Muslims or other agendas.