That's not quite accurate. 501(c)(3) nonprofits CAN engage in political activity. They are just limited in the amount they can do. A group like the Sierra Club

That's not quite accurate. 501(c)(3) nonprofits CAN engage in political activity. They are just limited in the amount they can do. A group like the Sierra Club whose primary activity is lobbying and politics and who incidentally does other things wouldn't fit under 501(c)(3).