The PGLE (Premier Grand Lodge of England), along with those jurisdictions with which it was in amity, later came to be known colloquially as the "Moderns", to distinguish them from a newer, rival group of Freemasonry, known as the "Antients." The Antients broke away and formed their own Grand Lodge in 1753, prompted by the PGLE's making changes to the secret modes of recognition. Tensions between the two groups were very high at times. Benjamin Franklin was a "Modern" and a deist, for instance, but by the time he died, his Lodge had gone "Antient", and would no longer recognize him as one of their own, declining even to give him a Masonic funeral (see "Revolutionary Brotherhood", by Steven C. Bullock, Univ. N. Carolina Press, Chapel Hill, 1996).
The schism was healed in the years following 1813, when the competing Grand Lodges were amalgamated, by virtue of a delicately worded compromise which left English Masonry clearly not Christian, returned the modes of recognition to their pre-1753 form, kept Freemasonry per se as consisting of three degrees only, but which was ambiguously worded so as to allow the Moderns to think of the Antient Royal Arch degree as an optional higher degree, while still allowing the Antients to view it as the completion of the third degree (see [1] (http://freemasonry.org/psoc/pragmatic.htm)).
Because both the Antients and the Moderns had "daughter" Lodges throughout the world, and because many of those Lodges still exist, there is a great deal of variability in the ritual used today, even between UGLE-recognized jurisdictions. Most Lodges conduct their Work in accordance with an agreed-upon single "Rite," such as the "York Rite" (which is popular in the United States), or the "Canadian Rite" (which is, in some ways, a concordance between the Rites used by the "Antients" and "Moderns").
The second great schism in Freemasonry occurred in the years following 1877, when the GOdF started accepting atheists unreservedly. While the issue of atheism is probably the greatest single factor in the split with the GOdF, the English also point to the French recognition of women's Masonry and co-Masonry, as well as the tendency of French Masons to be more willing to discuss religion and politics in Lodge. While the French curtail such discussion, they do not ban it as outright as do the English (see [2] (http://bessel.org/masrec/france.htm)). The schism between the two branches has occasionally been breached for short periods of time, especially during the First World War when American Masons overseas wanted to be able to visit French Lodges (see [3] (http://www.bessel.org/recfranc.htm)).
Concerning religious requirements, the oldest constitution of Freemasonry (that of Anderson, 1723) says only that a Mason "will never be a stupid Atheist nor an irreligious Libertine" if he "rightly understands the Art". The only religion required was "that Religion in which all Men agree, leaving their particular Opinions to themselves" ([4] (http://www.2be1ask1.com/library/anderson.html)). Masons disagree as to whether "stupid" and "irreligious" are meant as necessary or as accidental modifiers of "atheist" and "libertine". It is possible the ambiguity is intentional. In 1815, the newly amalgamated UGLE changed Anderson's constitutions to include more orthodox overtones: "Let a man's religion or mode of worship be what it may, he is not excluded from the Order, provided he believes in the glorious Architect of heaven and earth, and practices the sacred duties of morality." The English enforce this with a requirement for belief in a Supreme Being, and in his revealed will. While these requirements can still be interpreted in a non-theistic manner, they made it more difficult for unorthodox believers to enter the fraternity.
In 1849, the GOdF followed the English lead by adopting the "Supreme Being" requirement, but there was increasing pressure in Latin countries to openly admit atheists. There was an attempt at a compromise in 1875, by allowing the alternative phrase "Creative Principle" (which was less theistic-sounding than "Supreme Being"), but this was ultimately not enough for the GOdF, and in 1877 they went back to having no religious entrance requirements, adopting the original Anderson document of 1723 as their official Constitutions. They also created a modified ritual that made no direct verbal reference to the G.A.O.T.U. (although, as a symbol, it was arguably still present). This new Rite did not replace the older ones, but was added as an alternative (European jurisdictions in general tend not to restrict themselves to a single Rite, like most North American jurisdictions, but offer a menu of Rites, from which their Lodges can choose.)
Books You Might Enjoy:
Henry Cornelius Agrippa - Of Geomancy
Captain William Morgan - The Mysteries Of Freemasonry
Castells - The Apocalypse Of Freemasonry
