The IRS Can Censor Your Pulpit

This past Sunday, the Alliance Defense Fund expected nearly 500 church pastors nationwide to participate in "Pulpit Freedom Sunday." The event, organized for four consecutive years by ADF, is designed to challenge a 1954 amendment to the
501( c) 3 tax code that doesn't allow nonprofits to participate in political campaigns. The law is often referred to as the "Johnson Amendment" because Lyndon Johnson, a U.S. Senator at the time, introduced and advocated its passage.

As Richard Hammar explains in the 2011 Church & Clergy Tax Guide:

This limitation has an unusual and unfortunate history. It was proposed in 1954 by then Senator Lyndon B. Johnson of Texas as a floor amendment to the tax code, and it was passed without explanation. Apparently, Senator Johnson was attempting to limit the political activities of a private foundation that had supported one of his opponents in a Texas election. It is clear that few, if any, Senators contemplated in 1954 that the newly enacted limitation could be used to threaten the tax-exempt status of churches. However, the limitation is worded in absolute terms—prohibiting any attempts by churches or any other tax-exempt organizations to participate or intervene in a political campaign—and therefore does pose a significant threat to churches.