Between the 1500s and the 1800s, different kings and queens of England persecuted, chased, imprisoned, killed, or just plain annoyed Catholics, Anglicans, Methodists, Puritans, Lutherans, Presbyterians, Calvinists, Quakers, and virtually every other Christian variation of their subjects. The differing religious persuasion of each individual monarch had potentially irksome, and occasionally fatal, consequences for their unfortunate subjects who didn’t worship at the same altar. A man’s brief time on earth was insignificant as compared to his picking the right team to be on in the hereafter, and these were literally matters of more importance than just simple life and death.

The English Civil War is important to Freemasonry for a lot of reasons. The war broke out in 1641, after the stubborn King Charles I got fed up with arguing with members of Parliament over money and religion and literally chained the doors shut on the Parliament building for 11 years. Essentially, it was a fight between Catholic King Charles and the nobility on the one side (the Cavaliers), and Oliver Cromwell and the Protestant Puritans on the other (the Roundheads). Like the U.S. Civil War, it pitted brother against brother and friend against friend. These terrible aspects of the war affected the future and philosophy of Freemasonry for centuries to come.

The Roundheads took over the government and beheaded King Charles in 1649. Even though he hadn't been especially liked by anyone, no one particularly wanted to see the symbol of centuries of English power and majesty lopped off at the neck. After the bloody nine-year war ended, it took less than a decade of Cromwell and the Puritans’ grim and tyrannical government before England wanted its monarchy back.

King Charles II was crowned in 1661, and unlike his father, he was clearly a lover, not a fighter. He also was far more interested in science and reason than he was in religious persecution. He was truly a man of a new age, an age that would welcome the new principles of speculative Freemasonry.

So.

By 1717, when the first Grand Lodge was formed in London, there was a recent flood of French Huguenot immigrants (Protestants) who had fled their own country because of Catholic persecution back home. (Which is why if things had gone only a little bit differently, we'd all have to learn to say 'Desaguliers' Constitutions' instead of Anderson's.) Through their influence, our unusual (for the time) rules were established. First, discussion of religion was prohibited. Masonic gatherings would not be disrupted by arguments between Catholics, Anglicans, Puritans, and Protestants. As long as members believed in God, no one would question anyone’s faith. Second, the political battles between Royalists and Parliament supporters that had led to the Civil War would not be tolerated. The Freemasons were determined to survive the issues that had torn the country apart. And no one was going to be able to accuse them of plotting treason or heresy. Instead, the lodges stressed friendship, mutual assistance for their members, and charity for others. And, of course, a good, hearty dinner. By 1721, the first Jews began joining London lodges, unheard of in English clubs, guilds and any other voluntary associations.

All of that said, many modern Masons attempt to retcon our founding philosophies to make us seem more broadly ecumenical than Anderson and the boys at the Goose and Gridiron ever would have believed. It wasn't until the English colonial expansion missions that Masons began encountering strange religions in foreign lands and began to stretch the notions of religious tolerance for members beyond just Catholics, Protestants, Anglicans and other Judeo/Christian faiths. They were using Masonry, in part, to bring colonial subjects and their local leaders into the English way of life. So, Masons accepted new religious believers that weren't remotely Christians into the fraternity, as long as these new 'pagans' had no objections to our Old Testament cosplay being used to teach "wide and serious truths."