Let's propose an application to the IRS for a 501(c)4 organization. The original law in 1913 and thereafter to establish such 501(c)4 was that such were to EXCLUDE politics. So let's consider what politics is or isn't.
Education is a political process. A good teacher is a good politician who can inspire and lead by communication. If a teacher teaches evolution, the teacher is in opposition to groups who want creationism. Providing such information is social welfare at the same time it is politics. The groups will engage in political discourse and lobbying. If a group teaches that abortion should be made illegal, it does so by engaging in politics. Providing such information is social welfare at the same time it is politics. Such different political views were part and parcel of many of the applications to the IRS.
If applicants want to distribute handbooks of the US Constitution, or bookmarks with parts of it, that's education which is also political training in the Constitution that is also done in schools. Providing those for free is social welfare.
Some applicants believe that telling lies about their opposition candidates is also educational and social welfare, as they sincerely believe they are doing things better than the opposition.
So communicating at all is a form of social welfare. An important question is whether communication should be subsidized outside of educational institutions.
So let's take a possible scenario:
A group naming itself "The True Education of Reality" wants to be tax-exempt.
They would have to submit an application to some agency that would have to have some rules.
The group's purpose is to pray in silence to 'sacrifice children to the Supreme Underworld Master' in order to educate the public about the value of human life.
However, to ask them the content of their prayer is discriminating against their religious beliefs.
The problem here is that Christian groups complaining about being asked the content of their prayers can't conceive of any other religion doing things other than they do, so no religion should be disclosed to get a tax deduction.
Sometimes educating people in a religion is very political. The IRS shouldn't be required to ever get near such judgements, Accountants are usually at the back if the line in colleges for learning humanities and social services. Tax exempt status makes for too many problems and the IRS practice of examining politics should be dropped. Congressmen can then decide which of their donors gets the pork of corporate welfare.