--"giving money to others makes us more happy overall than using that money for ourselves". Of course, there are obvious examples where that is not the case e.g. tax or alimony. And an example of giving pleasure with out there being obvious self interest: paying your partner's credit card bill. That's altruism.

Anonymous, you wrote: "an example of giving pleasure with out there being obvious self interest: paying your partner's credit card bill. That's altruism." Paying a partner's credit card bill, or doing anything considerate for a loved one, benefits the relationship, and thus you. The real question is, is it altruism even if there's no clear benefit? Because self-sacrifice brings self-satisfaction, which itself is a benefit.

Jesus is considered by many to be altruistic. Yet he is quoted to saying not my will but yours be done.
He is responding to fear of disapointing is God (father), or he is seeking approval of his God (father). Which does not seem to show him as altruistic.

Why is altruism axiomatically considered "the good" and self-interest "the bad". The morality of an action can't be defined simply on the basis of who benefits (if I robbed you, but gave the money to someone else, then I [the actor] would not be benefitting from my action, but it's still clearly immoral).

Rational self interest is a good thing. Altruism essentially requires the sacrifice of an individual (or something of them), so it's bad.

"Objectivist much?".

If you really wanted to be "altruistic" (i.e. you don't benefit), then shouldn't you donate to a cause you don't believe in?

I believe there is some evidence (Sara Algoe) that the giver needs some feedback (a thank you, or the happy reaction of the receiver) to feel this sense of happiness (so giving to a cause that you don't believe in may warrant some good feeling, given that they're grateful). However, I don't think this feeling is in the same category as hedonism, because this is a moral decision. It likely relates to Haidt's "elevation", don't you think? When people mention wanting to change the world, usually they are referring to increasing the well being of a group of people or people in general, and this would be more related to meaning than to pleasure. Either way, would not getting this sense of meaning make it more respectable, admirable or worthwhile? Isn't altruism as it is (untrue) just fine?