Like with religion, sexual preference, diets can be an emotion filled topic, especially the topic of to eat meat or not to eat meat. I have thought and ran across theories about this topic for years. My spiritual beliefs is that all living things have an energy field, hence a soul. I also believe that we humans incarnate with goals and lessons in our lives.
Okay with that said here are some thoughts you take it or leave whatever doesn't work for you. I am not in the business to judge! I'm just putting these thoughts out there that has made me ponder over the years.
When I was in massage school I had a teacher that was talking vegetarianism and my friend looked at me and said "Like a radishes is happy to be pulled" Which got me thinking. I believe a radish has an energy/soul and by pulling the radish you stop it's growing life. Is that different from taking an animals life? Makes you stop and think.
So if we incarnate with a life purpose what about animals? Do they have a mission or purpose? If you really think about it and I have. Most every animal ends up as food. A rabbit is food for a hawk, a mouse for a snake, deer for a coyote, cow for a human, or decaying body (or plant)for bugs. Everything eventually gets eaten in some way shape or form.
So does an animal(human) come to the earthly plane to be a food source? Kind of seems like it if you think about it that way.
I live in the Midwest where I often see livestock trailers headed to the packing plants. For each one I say this pray, knowing that meat will always be eaten that will not change. I say "God, please let these animals have a calm and quick death and may they know the love and gratitude we have for them as they give their life so that we might be able to live."