Okay, it’s not. But it should be. From The Dawn of Freedom of Religion in the West:
Today is the anniversary of King John Sigismund’s Edict of Torda in 1579. It established the right of ministers to preach the gospel as they best understood it, and, as well, for congregants to reserve their own opinions in these matters….
For a brief overview of the place and time and its principal players and most notably the preacher Francis David who inspired the King to this action, I recommend the late Dr Frank Schulman’s sermon “God is One.”
Hurrah!
And, yes, the idea of religious freedom is ancient. But Constantine Christianity missed the parts of Jesus’s teaching that say those who are not against us are for us, so it took a unitarian king to restore religious freedom in Europe. Alas, trinitarians took over after his death, but the memory of that religious Camelot lives on.
P.S. The United States has a provincial Religious Freedom Day in January, but if the world’s Christians want one, today is better.
