I think it is simpler, any act of omission or commission that make the world a worse place is immoral, a greater or lesser sin. Pretty much we all just take and don't give back much, so we are all net sinners. We are often given choices between two evils and strive to pick the lesser of the two evils. The lesser sin is better. You can try to make an argument that good intentions should count for something, I would counter that only outcomes matter. "The road to hell is paved with good intentions."

The kitten analogy is maybe apt. Is the world better or worse because he killed a kitten, maybe killed many kittens. It is hard to say but it could be parsed. Where did the kitten come from, what was going to happen to the kitten if he did not kill it. Guessing the individual is depraved and was killing for the pleasure of killing, has no direct bearing on the morality of the kitten killing. The kitten is dead, will not be using planetary resources, will not grow up to kill songbirds, will it deprive someone of a beloved pet, hard to say. Seems the world is a better place because he killed the kitten. On the flip side, what becomes of him, will killing the kitten lead to other killing that will not be a beneficial for the planet or will the killing of an occasional kitten satisfy his depravity and actually prevent him from committing some sinful violence.

Another apt reference was your declaration that meat eating is immoral. This is almost certainly true in most instances. Eating meat that is bought from typical supplier is causing harm to the planet. Causing more harm to the planet that other diets you could choose, you could choose a lesser evil. There could be moral meat eating, I could go shoot an invasive feral pig, they are causing a lot of environmental damage around here, killing and eating that pig would almost certainly be moral. It would actually be a double win, stop the pig's damaging ways and eating the pig would mean I would not be eating something else that was produced in a manner that was damaging to the planet. You see it is not meat eating that is immoral, it is the over consumption of limited resources.

Morality is about good, bad or worse. Socially correct, right and wrong are not really about morality but more about social stability, this does have a moral aspect because social instability can lead to destruction and unhappiness. There is an aspect of going along to get along is the morally right thing to do. Not killing kittens might lead to consumption of planetary resource and potential local extinction of bird species but social unrest caused by rampant kitten killing would probably be worse. It is a slippery slope, killing things that use up planetary resources.

While the thought that the less sinful of us might enjoy some sort of afterlife might be comforting, it seems unlikely.

TEK