Armando Valladares

is the author of the best-selling memoir "Against All Hope" and the recipient of the Becket Fund's 2016 Canterbury Medal

In December of 1785, George Washington received a letter from Quaker abolitionist Robert Pleasants pleading with him to make a priority of ending slavery. Eighty years later - 150 years ago this month - he got his wish. This month marks the sesquicentennial of the ratification of the 13th Amendment, which officially ended the scourge of slavery in America.

Washington and the presidents that came after him received many more letters from abolitionists. Most of them were from Quakers, who played a pivotal role in turning antislavery sentiment in America into the organized grassroots campaign that eventually became known as abolitionism.

The Quakers were effective and adamant campaigners because they learned about fighting for one's rights firsthand. Considered religious radicals in their day, the Quakers experienced religious hostility and persecution for their beliefs and practices, ranging from pacifism to the refusal to swear oaths. They lobbied for recognition for their religious rights, which included their own letter exchanges with Washington.

Many consider Washington's Letter to the Annual Meeting of Quakers, in which he wrote, "The conscientious scruples of all men should be treated with great delicacy and tenderness," to be one of the most important iterations on religious liberty from the founding era. Before the Quakers shaped the course of American history with regards to slavery, they firmly put their imprint on its course with regards to religious liberty.

If only they had come to Cuba before I left for Florida. I spent 22 years of my life in Castro's jails over one conscientious scruple: my refusal to pledge allegiance to Castro.

Because I would not put a sign on my desk that said, "I'm with Fidel," I was carted off to jail at gunpoint, and a kangaroo court condemned away decades of my life. But though the Quakers never made it to my island, I survived the most hideous torture and oppression for the same reasons that they did: faith. Indeed, it was that pesky mustard seed that, if you have it, to quote Jesus himself, "Nothing will be impossible for you."

It was my faith that informed my sense of inner freedom, despite my internment. Though my body was in prison, my mind was free. This was more than a feeling, this was a truth that I had learned from my own Catholic faith. As the church puts it in Dignitatus Humanae, the church's 50-year-old formative text on religious liberty, "Therefore the right to religious freedom has its foundation not in the subjective disposition of the person, but in his very nature."

My subjective disposition for 22 years was imprisoned, but my nature was unchanged. And indeed it was this knowledge that helped me do the impossible: survive the torture and abuse of Castro's thugs for years on end.

Though the Founders lived long before the church offered what is perhaps the clearest writing on the essential religious rights of all men and women, their experiment in religious liberty was founded on the same appeal to natural law. It is man's own nature that makes him free to pursue the truth as he sees fit, not the decrees of dictators who dole out freedom based on their arbitrary whims. The early abolitionists got this; it inspired their own understanding that slavery is an affront to natural law and human rights.

It should come as no surprise, then, that most social justice movements in America were steered by men and women of faith. The mustard seed of faith opens the mind's eye to the human dignity that hums in each of us. The Quakers drove the fight against slavery, the leader of the civil rights movement that followed was a Baptist minister, and it was Catholic priests who denied communion to segregationists.

And though my body is now free, the bodies of so many others around the world are locked up because they have the audacity to be true to their minds. Even in the postmodern age, and, yes, despite "warming relations," even in Cuba, prisoners of conscience, most especially prisoners for their faith, are everywhere.

As Robert Pleasants asked Washington on the subject of slavery, "How can we expect to do such violence to Human Nature in this enlightened age with impunity?" The answer is that we won't.

The sacred rights of man can never be violated without the eventual cascading of repercussions. But it is the inner certainty of the inviolability of freedom of conscience, planted by the seed of faith, that gives so many the hope, courage, and strength to fight for what is rightfully theirs for just one more day.