I guess Rick Willes has a problem with the Franciscans, Trappists, Trappistines, Carthusians and Cistercians orders that can be vegetarian for faith based reasons.
The most obvious reasons is to combat the sin of gluttony, through abstinence. Given that people are starving on this planet and that a meat diet takes more land and energy than plant based diet, it could be argued that it would be Christian to abstain to ensure that all humans can share in what god has provided.
Old Testament style— God said, “See, I have given you every plant yielding seed that is upon the face of all the earth, and every tree with seed in its fruit; you shall have them for food. And to every beast of the earth, and to every bird of the air, and to everything that creeps on the earth, everything that has the breath of life, I have given every green plant for food.” And it was so.