It may be apocryphal, but one part of the story of Masada is that the male heads of families, who had to kill their wives and children, received instruction beforehand on how to do it in the ritual manner to avoid causing their loved ones suffering. If the animals are drugged the drugs end up in the meat and consumed. So "put to sleep" method is out. My father, who was a lifelong hunter told me that immediately hanging the carcass of a deer up and draining the blood from it is necessary to avoid the meat becoming "gamy" and all but inedible. Any way it's done it cannot be entirely painless to the animal and in my opinion there's nothing wrong with someone choosing to be a vegetarian for reasons of conscience. Forcing everybody else to go along is.
In terms, as you put it, of a "Godly" procedure the method prescribed by Judaic tradition is probably about as close as you can get without avoiding meat, fish, or fowl altogether. And it's worth noting that the people pushing these prohibitions against a practice dating back thousands of years are the same ones who are trying to ban Jewish circumcision, and the wearing of yarmulkes and crosses by Jewish and Christian believers. It is part and parcel of an effort to ban all but the worship of the state that goes back at least to the French Revolution.
Are they the same people? I thought it was animal rights groups in particular. And I just don’t know whether there’s been an advancement in nonpainful killings or not.
I agree vegetarianism should be voluntary, but I don’t think there’s any bit of moral superiority to it: in our world if animals don’t have jobs providing some kind of products to people, they mostly don’t exist. I’d rather have animals raised humanely and eaten than not raised at all.