What is it and why do Freemason’s note it?
St. John the Evangelist, along with St. John the Baptist are the two St. John's referred to in Masonic ritual; “The Holy Saints John”.

The feast of John the Baptist falls on 24 June, and that of John the Evangelist on December 27, roughly marking mid-summer and mid-winter.
During the Eighteenth Century, the Premier Grand Lodge of England and the Grand Lodge of Ireland favoured the day of John the Baptist, (note the formation of the Grand Lodge of England on St. John the Baptist’s day June 24, 1717). The Grand Lodge of Scotland, the Ancient Grand Lodge of England and the Grand Lodge of All England at York installed their Grand Masters on the feast day of John the Evangelist.
The Evangelist is particularly associated with Scottish lodges. The Lodge of Edinburgh was associated with the aisle of St. John the Evangelist in St. Giles Cathedral in Edinburgh from the 15th century.
The Grand Lodge of All England, and its predecessor, the Ancient Society of Freemasons in the City of York, elected and installed their President, then from 1725 their Grand Master, on the day of the Evangelist, and in London the Antient Grand Lodge of England elected their new Grand Masters on the same day.
When the Antients and the Moderns (the Premier Grand Lodge referenced above) eventually came together to form what we now know as the United Grand Lodge of England, it was on the Feast of the Evangelist on December 27, 1813.
All quite interesting, you might be thinking. But the question still begs: Why do Masons mark these feast days?
Virtually all of the operative guilds of the Middle Ages had patron saints. The Masonic guilds were no exception. In each case the feast day for their patron saint became an important day for celebrations, installations etc.. It seems that St. Thomas, early on, was often a patron saint of Operative Masonic Lodges. The Regius Poem (aka the Halliwell Manuscript) which dates to the turn of the 15th Century implies that the Four Crowned Martyrs (Quatour Coronati) had a role as patron saints. Regardless, by the 17th Century, one or the other of the Saints John are noted as patron saints of Lodges.
The Holy Saints John are logical choices for a fraternity dedicated to seeking light. Their feast days occur near the summer and winter solstices. Also, important Masonic lessons can be drawn from their exemplary lives.
So who was St. John the Evangelist and why should he be important to Masons?
Our ancient Brethren would have known him as the “beloved disciple” of Christ who was the author of four books in the Bible’ the Gospel of John, First and Second John and the Revelation of St. John the Divine. There is some scholarly debate about this point, but humour me and let’s agree that for the purpose of this evening’s talk, John was indeed the author of the above mentioned books in the Bible.
This is the St. John the Evangelist to whom our ancient brethren chose to dedicate their Lodges. It is through these writings that we know him, and it is through these writings we find the basis for dedicating our Lodges to him.
St. John is revered as an author with exceptional spiritual insight.
He is the patron saint of love, loyalty, friendships and authors. He did not flee when Jesus was arrested. He apparently attended the trial and was at the foot of the cross when Jesus was crucified. At that point he was entrusted by Jesus with the care of St. Mary, Jesus mother; so he was there at the end. (Note; John the Baptist, in contrast, was with Jesus at the beginning of his ministry) – again... bookends?
Who better to be a patron saint of Freemasonry than the patron saint of love, loyalty and friendships? In addition, he is committed to seeking the light.
Summary:
Why is St. John the Evangelist important to Freemasons?
There is a long history of Masonic Lodges being dedicated to him. One that appears to predate speculative Masonry.
His feast day near the winter solstice and his appearance at the cross are natural bookends to the feast of St. John the Baptist near the summer solstice and his role at the beginning of Jesus public ministry.
His example of friendship and loyalty and the focus he placed on the importance of brotherhood and seeking and living within the light in his writings is consistent with the focus Freemason place on those attributes.
His is the patron saint of Love, Loyalty and Friendships. All of these are values Freemasons treasure.
Excellent post!!