People follow a vegetarian diet for a few reasons. Sometimes it is medically necessary (Allergies, for example), or for a religious purpose, or for a movement in order to not eat animals, or just a preference not to eat meat. It varies per individual. Some just do it because that was how they were raised, too.
It's more by a matter of choice due to weight concerns and health, concerns for animals (be it rights, welfare, or extremist views that animals aren't meant for humans to eat), concerns for the environment (some believe that eating less or no meat is better for the environment), or beliefs that eating more plants and grains will free up more food for those who don't have enough to eat. Whatever the choices, none of them are right or wrong no matter who says what.
You will get both vegetarian and non vegan food there
素食 (vegetarian/vegan food in general) 齋 (vegetarian/vegan, less often used unless in the religious sense)
Salads or soy milk
Most foods served in a langar is considered vegetarian but not vegan as milk, cheese and butter fats are almost always used.
Yes some Adventists eat chicken. It is not prohibited, as it is a kosher meat, however a majority of Seventh-day Adventists are vegetarian. If you are considering preparing food for a group of Seventh-day Adventists, it may be better to prepare a vegetarian meal.
Most recipe books and online food sites will have a section catering to vegetarian and or vegan diets. Make sure that you are clear about your dietary restrictions before buying food.
Real Food Daily, Cru, Flore, Vegan Glory
Some vegetarian diets include the Vegan diet. I believe they eat special types of food and no meat as vegetarians do. You can also find more on the computer.
Consult with a good deli; they might have some. A great, meltable vegan mozzarella is by Follow Your Heart and can be found at health food stores or online (such as veganessentials.com).
Unless all your guests are vegan you should have a variety of foods. If you do not wish to do this then where it says Reception on the invitation put 'Vegan Food Served' and in brackets put what that means as some of your guests may not have any idea what that is. It does not need to be specified, but if you feel the need to mention it, write 'Vegan friendly food available.' All- Vegan Weddings are becoming more and more common. It is not necessary to accommodate non-vegan guests as suggested by some. Vegan foods are suitable for vegans, vegetarians, and omnivores. It should not need to be mentioned on the invitation.
There are a number of websites that carry recipes for vegan crock pot chili. One can find such recipes on 'allrecipes', 'The Lazy Vegetarian' and 'Food Network'.
The title can be as simple as "Why vegetarian diet is unhealthy". However, I personally don't think they are. A vegetarian can get a very balanced food daily and its a myth that non-vegetarian food is essential or better. I am myself a Vegan for more than 10 years and I know such people who are so for more than 30 years. All of us are very healthy, much better than most of the people around!