I don’t think you can equate birds eating slugs to throwing Christians to the lions. Maybe that particular vegan gardener should have found a dark place to rehome said slugs, however, slugs are common food for birds, frogs and other species they are adept at picking them out from plants and from seemingly dark corners . I don’t think lions in the wild would necessarily seek out Christians as a major food source. The difference is, humans in the West mostly have some choice about what they eat, birds and other wild creatures have fewer choices and will only eat what is immediately available in their habitat. Yes, humans can survive in many different environments, but in many countries these days, meat is not an essential part of human diet, we can live quite healthily on little or no meat if that is your choice. It’s not compulsory to eat meat in our complex society, any more than it is compulsory not to - it’s a choice. If you choose to eat meat, fine, that’s your choice, just as not eating it is a choice. people make their choices for many different reasons - habit, income, family pressures, ethical or environmental concerns. No one can say others are “right” or “wrong”.