isn't this why the government gives tax breaks to people that voluntarily contribute to charitable organizations?

Yeah, it is and that's a good thing for the most part, except it's all the exemptions that cause the tax code to be so complicated.

FWIW, I don't think the path to getting to my ideal is to cut all social programs and rely on personal mercy to do the trick- though our government IS spending to much and needs to start cutting back somehow. I think the real ultimate path is to move people to take responsibility for mercy and thus lessen the need for government intervention. I'm not totally certain that the government will lessen taxes if social needs get met outside of it's programs though; more likely is new social programs will be developed to consume spending.