The Bhagavad-Gita is an empire of thought and in its philosophical teachings Krishna has all the attributes of the full-fledged montheistic deity and at the same time the attributes of the Upanisadic absolute.
'Thou shalt not kill' does not apply to murder of one's own kind only, but to all living beings and this commandment was inscribed in the human breast long before it was proclaimed from Sinai.
I do feel that spiritual progress does demand at some stage that we should cease to kill our fellow creatures for the satisfaction of our bodily wants.
Philosophical knowledge is the knowledge gained by reason from concepts ; mathematical knowledge is the knowledge gained by reason from the construction of concepts.