Mike Pence made it very clear that he is first and foremost a Christian. In other words he is committed to discriminating against the LGBT community. How will Log Cabin Republicans reconcile this? What about Paul Singer? After all, the suggestion is that Christianity is the national religion. But I digress.
The Johnson Amendment (which has been part of the tax code since 1954) prevents contributions to political campaigns from being tax deductible. As the IRS explains:
Under the Internal Revenue Code, all section 501(c)(3) organizations are absolutely prohibited from directly or indirectly participating in, or intervening in, any political campaign on behalf of (or in opposition to) any candidate for elective public office. Contributions to political campaign funds or public statements of position (verbal or written) made on behalf of the organization in favor of or in opposition to any candidate for public office clearly violate the prohibition against political campaign activity. Violating this prohibition may result in denial or revocation of tax-exempt status and the imposition of certain excise taxes.Each year, Alliance Defending Freedom engages in a day of defiance getting pastors to endorse political candidates. The sole objective is to get the IRS to take action by revoking the tax-exempt status of an offending church. ADF wants to get the Johnson Amendment before the Supreme Court on the premise that it is unconstitutional on First Amendment grounds. Unfortunately the IRS lacks the will to take action in spite of being on solid ground.
The precedent is Branch Ministries v. Rossotti. In 1999 the federal district court ruled in favor of the IRS by summary judgment. In 2000 this was upheld by the Court of Appeals for the District of Columbia.
That may all be academic since the President of the United States cannot change the tax code. That has to be done by legislation. I am guessing that people saner than Trump (which is most of the planet) on both sides of the aisle are not in favor of this kind of free-for-all.