Spiritual

Orthodox Buddhists and Hindus have always been vegetarian and often vegan for their religions are founded on the belief that life is sacred - not just human life, as in Christianity - but all life. But, just as importantly, both these great religions also teach that not only is a vegan diet correct in ethical terms, but that it is also more conducive to spiritual peace of mind and the acquisition of the virtues of humility and compassion. Christians have, of course, always admired just these two virtues above all else in their own founder and leader, so it is odd how little heed is paid to his own words on the subject:

"Not by shedding innocent blood, but by living a righteous life shall ye find the peace of God... Blessed are they who keep this law; for God is manifested in all creatures. All creatures live in God, and God is hid in them...
"The fruit of the trees and of the seeds and of the herbs alone do I partake, and these are changed by the spirit into my flesh and blood. Of these alone and their like shall ye eat who believe in me and are my disciples; for of these, in the spirit, come life and health and healing unto man..."
    From The Gospel of the Holy Twelve, trans. by G. J. Ouseley.

It would seem that the Jesus in this apocryphal gospel is advocating veganism. In another early gospel, translated into English directly from the Aramaic tongue Jesus is thought to have spoken, there is a specific warning of the dire consequences of the killing and eating of animals:

"And the flesh of slain beasts in his own body will become his own tomb. For I tell you truly, he who kills, kills himself, and whoso eats the flesh of slain beasts, eats the body of death."
   From The Gospel of Peace of Jesus Christ by the Disciple John, trans. by E.B. Szekeley, C.W. Daniel, London, 1937.

But isn't it enough to be vegetarian? Why become vegan?

The problem is that the industrial production of milk, butter, eggs and cheese is totally dependent on the existence of the rest of the factory farming industry with all its odious practices. Repeated frustrated pregnancies are required to keep dairy cows lactating and in any case they are slaughtered for meat as soon as their milk yield drops, and it is the fate of their unfortunate calves to be removed from their mothers at birth and sent either straight to the slaughterhouse or to veal production units. Most eggs come from battery systems of course (including those with names like 'Farm Fresh') but even free-range egg production entails the killing of the unproductive - the cocks (only half a a batch of fertile eggs will hatch into hens) and even the productive hens are sent for slaughter as soon as their laying days are over.
   So we see that even buying a carton of milk in a supermarket or half a dozen free-range eggs in a wholefood shop makes a tiny, but significant, contribution to industrial slaughter.