The most famous conscientious objector during the Vietnam War was a fighter. Muhammad Ali fought with his fists to earn the title of “the greatest.” More important, he fought for his beliefs. “My conscience won’t let me shoot my brother,” he said of the Vietcong, with whom he claimed to have no quarrel. “They never called me nigger.”

For defying the government’s call to kill, the fighter who refused to fight was banned from boxing for three years. Rejecting military induction made him a polarizing figure for a time but over the years built his legacy as a model of courage and principle.

History vindicated Ali. In 1971 the U.S. Supreme Court overturned his conviction for resisting the draft. After his death 45 years later, eulogists praised him for an act that once brought scorn.

“I believe in Allah and in peace,” Ali said, citing the parts of his identity that made him a pariah. But in 2016, the world embraced him. Fond remembrances of Ali — a Muslim and a war resister — showed how far the United States has comes in respecting diverse beliefs.

Yes, there is evidence to the contrary: Suspicion of Muslims, immigrants, racial and sexual minorities persists. Even now, prejudice seems to be rising. And yet there is a certain desperation in the hateful words and spasms of violence — an empty recklessness that marks them as exceptions to the tolerant direction in which we pray the arc of history is bending.

Propelling this hopeful trajectory is respect for conscience and religious freedom. As if to emphasize its importance, the liberty-of-faith guarantee comes first in the First Amendment’s list of freedoms. It’s enough to make Independence Day worth celebrating all by itself.

More than two centuries before the Bill of Rights, the Anabaptists pioneered the principle of religious freedom. They were far ahead of the other 16th-century reformers, who claimed to be bound by conscience but refused to extend the same freedom to others. Martin Luther defended his own defiance of the pope because “it is neither safe nor right to go against conscience.” But when it came to other people’s heresies, he stood with those who thought religious liberty would lead to social chaos.

True freedom of religion requires church-state separation, which most reformers could not imagine. But the Anabaptists did. In fact, some went a step further: They could see that dividing the church from the state would lead to religious pluralism. Hans Denck was ahead of his time when he envisioned a society with various types of Christians and even “Turks and heathen and Jews” living side by side. Some Christians today still resist Denck’s inclusive worldview.

History vindicated the Anabaptists. Church-state separation became a cornerstone of democracy. Mennonites have a special appreciation for religious freedom because of our history as immigrants and conscientious objectors.

Freedom of conscience ensures that people have the right to act on their moral choices. It requires each of us to respect the moral choices of others. A peaceful society is not possible without it. We are grateful to live in a world shaped by the ideas and actions of conscience-following rebels like Mu­hammad Ali and Hans Denck.