Your holy book tells the story of his crimes against humanity. Most likely what really happened is barbarians wanted to kill, rape and pillage and later claim some Jewish sky wizard told them to do it.
<quoted text>If you reject that there is a God, then God ordered no killing, it was just man deciding to kill. Now, if you accept as you claim that God ordered a killing, then you accept that He is Go and not a man. So, that his killing is even less so than you killing time or killing an ant. I am certain that the ant screams at you "murderer". Also, consider that you to God are another life form, like plants. So, each time you step on grass, the grass would scream " murderer, murderer".
On the other hand if you accept that animals and plants are here for our purpose, then you must accept that the giver of that purpose, God, put us here for his purpose.
The thing that you must know is this, God gives life and appoints the time. If you live to be 120, then so be it. If God decides that you are a waste of air and space, then your life may be cut-off at age 20. So, stop killing time, it may scream at you "murderer, murderer".