yes. thou shall not kill.

Context is everything. Whose god, and killing what or whom?

Yes because God said your not allowed to kill no matter what. oh and the thing with the crusades was that preists said you would go straight to heaven if you died in combat and if you lived they gave you land and stuff just so you would go fight for them.

In today's world the only ones who are killing in the name of God are Muslims.

Therefore you are asking if a Muslim can ever be justified in killing for a noble cause. The answer any Muslim will tell you is "Yes", this is possible. When he is defending Islam or when he is defending the weak from oppression, then the Muslim can kill in the name of Allah, in fact he is compelled to do so.

what about just a killing? Without any justifications?what about killing in the name of man made Law? Lets those without sin will trow the stone first....next question: would the One Without sin trow the stone? I can't imagine a Saint trowing stone in order to kill...Would you? Killing is a killing even a doctor would miss a mark while performing its duty...Who is a Judge? It is not possible to know and calculate everything..Oh it would be justified, given different name, put under another Law...Actually our current justice is all about...

Yes. Aside from the morality of killing, as regards the morality of using God's name to do it:

'Tis sweet, sweet poison to say "Thus saith the Lord" after one's own opinions.