The free exercise of religion — as protected by the U.S. Constitution — is under attack, an LDS leader says, and members of The Church of Jesus Christ of Latter-day Saints are being called upon to rally in its defense.

"There is a battle over the meaning of that freedom," said Elder Dallin H. Oaks of the Quorum of the Twelve. "The contest is of eternal importance, and it is your generation that must understand the issues and make the efforts to prevail."

He listed several examples of current controversies regarding religious freedom — laws governing marriage and adoption, laws regulating activities of church-related organizations in furthering their religious missions, and laws prohibiting discrimination in employment circumstances against people with unpopular religious beliefs or practices.

The former University of Chicago law professor, Brigham Young University president and Utah Supreme Court justice acknowledged during his devotional talk Tuesday afternoon at BYU-Idaho's Hart Auditorium that, thanks to the Internet age, his message would be received by an even wider, more diverse audience.

Christian principles of human worth and dignity made possible the Constitution's formation more than 200 years ago, and only those principles in the hearts of a majority of a diverse American population can sustain the Constitution today, he said.

"Religious values and political realities are so interlinked in the origin and perpetuation of this nation that we cannot lose the influence of Christianity in the public square without seriously jeopardizing our freedoms," he said.

"I maintain that this is a political fact, well qualified for argument in the public square by religious people whose freedom to believe and act must always be protected by what is properly called our 'First Freedom,' the free exercise of religion."

The Constitution's fundamental principle of popular sovereignty, which implies popular responsibility, allows individuals to act according to their moral agency and to be held accountable for those actions.

"In other words, the most desirable condition for the effective exercise of God-given moral agency is a condition of maximum freedom and responsibility — the opposite of slavery or political oppression," Elder Oaks said.

The Constitution contains a prohibition against "an establishment of religion," intended to prohibit a government-established church and avoid the types of national churches still found in Europe. The free "exercise" of religion, he added, involves rights to choose religious beliefs and affiliations and to practice those beliefs.