The Buddha, it is said, has limitless compassion for all beings. Yes. Absolutely. But that doesn't mean he would give himself completely to save others. This is very different from the Christian ideal. The Buddha would not die to "save" all souls. He would probably say that it doesn't work that way.
The Buddha's compassion, Thanissaro said in a talk I heard, was that he went out of his way to teach people. To help them. He didn't owe them. He had his enlightenment. And he knew there would be many troubles in his teaching. We think about all the monks who succeeded, but there were also problem monks, like the Group of Six were constant troublemakers. And the Buddha initially refused to teach at all. But, the Buddha decided it would be worth it after initially thinking that he wouldn't teach.
But his compassion didn't mean he taught everyone. In MN80, he lays out some conditions for his teaching:
“Let an observant person come—one who is not fraudulent, not deceitful, one of an honest nature. I instruct him. I teach him the Dhamma. Practicing as instructed, he in no long time knows for himself, sees for himself: ‘So this is how there is the right liberation from bondage, i.e., the bondage of ignorance.’” — MN 80
Let's break down this passage about "lost causes".
