During oral arguments for the Obergefell v.Hodges Roberts, C.J. case, Justice Alito asked Solicitor General Donald Verrilli whether universities that believe in traditional marriage might have their federal tax exemption challenged by advocates of same-sex marriage. Verrilli replied, "It's certainly going to be an issue. I don't deny that. I don't deny that, Justice Alito. It is -- it is going to be an issue."

In his dissent to same-sex marriage, Chief Justice John Roberts wrote, "Hard questions arise when people of faith exercise religion in ways that may be seen to conflict with the new right to same-sex marriage -- when, for example, a religious college provides student housing only to opposite-sex couples, or a religious adoption agency declines to place children with same-sex married couples. Indeed, the Solicitor General candidly acknowledged that the tax exemptions of some religious institutions would be in question if they opposed same-sex marriage."

What can be done to protect religious liberty? I have three suggestions.

First, Congress should pass the First Amendment Defense Act which would prohibit the Federal Government from taking action against an institution that opposes same-sex marriage by revoking a tax-exemption of barring them from receiving federal grants. This law would be a crucial shield protecting religious liberty.

Second, state governments need to pass similar laws. Kansas Gov. Sam Brownback issued an Executive Order this week to protect religious leaders and groups who do not approve of same-sex marriage. The order keeps state government from taking actions against officials and organizations "on the basis that such person or organization believes or sincerely acts in accordance with a religious belief or moral conviction that marriage is, or should be recognized as the union of one man and one woman."

Brownback acknowledged the Supreme Court's authority to force Kansas to recognize same-sex marriages for the first time. However, he said, "We also recognize that religious liberty is at the heart of who we are as Kansans and Americans and should be protected. Today's Executive Order protects Kansas clergy and religious organizations from being forced to participate in activities that violate their sincerely and deeply held beliefs," Brownback asserted.

Texas Gov. Greg Abbott also issued a "religious liberties directive" ordering Texas agencies to prioritize the First Amendment and ensure that nobody "takes any adverse action against individuals who are "substantially motivated by sincere religious belief."

These gubernatorial actions are commendable, but passage of a state law comparable to the First Amendment Defense Act, sponsored by Sen. Mike Lee of Utah and Rep. Raul Labrador of Idaho would give deeper protection.

The American Academy of Pediatricians asserted that "there should be little debate about the effects same sex marriage has upon children: Same-sex marriage deliberately deprives the child of a mother or father and is therefore detrimental."

The U.S. Conference of Catholic Bishops published a bulletin insert in Catholic churches on Sunday that attacked the court for "falsely redefining marriage, threatening religious freedom in numerous ways." It urged Catholics to "give witness to the truth of marriage," and to be prepared for false charges of discrimination."

The insert asked, "What is marriage?" USCCB President Archbishop Joseph Kurtz answered, "Marriage is the permanent and exclusive union of one man and one woman for the good of the spouses and for the procreation and education of children."

Finally, churches and other religious organizations need to take steps to protect themselves. Catholic Bishop Joseph Mattera recommended that church bylaws state that the church will not perform same-sex weddings, or allow its facilities to be used for one.

We must protect religious liberty, America's most important freedom.

Michael J. McManus is President of Marriage Savers and a syndicated columnist