A simple statement from a friend when discussed our common love for animals, 'If you love animals then why do you eat them?' set me thinking on how most religions, the Abrahamic as well as the Vedic, discourage meat eating.
Clearly meat eating is not banned in some of these, but it is discouraged indirectly. A very interesting common thread that runs through them all is that sacred or blessed food is almost always vegetarian such as manna, amrit or wine. According to one Hadith one must wash one's mouth after eating meat.
Sufism has a deep-rooted belief that vegetarianism is an essential step towards spiritual growth. Sufi saints like Rahim Bawa Mohiyuddin and Hazrat Rabia Basri showed love and compassion to animals and taught that mercy towards them is essential to Islamic mysticism.
A popular incident in Hazrat Rabia's life goes that whenever she retired to the forest to meditate, she was surrounded by animals and birds. But as soon as another Sufi approached, they ran away, which angered him and he asked her why they did so. In turn, she asked him what he had eaten. He replied that he had eaten onions fried in fat, at which she exclaimed, "You eat their fat! Why should they not flee from you?"
The Hadith also tell us that the Prophet Mohammed narrated the event of a prostitute who saw a thirsty dog standing by a well. Its tongue was hanging out and it was about to die of thirst. She immediately pulled off her leather sock (a part of Arabian dress), filled water in it from the well and gave it to the dog. Her sins were forgiven for that act of kindness, according to the Prophet. When I see miserable hens cooped up in cages, horses, mules or dogs being treated cruelly or animals being needlessly tortured, I realize the relevance of these religious teachings. One may or may not eat meat by choice, but it is clearly our moral responsibility to take care of all the creatures who share our Earth.