Before 1962, Jan. 1 was celebrated in the church as the Feast of the Circumcision, a tradition tracing back to the church celebrations in the East. In Western Europe, the date honored the Motherhood of Mary, but it was later eclipsed in prominence by the circumcision feast.
For several centuries, Jan. 1 was also the feast of the Holy Name of Jesus (now celebrated on Jan. 3). This was because, as recorded in the Gospel of Luke (2:21), Jesus received his name the eighth day after his birth, when he was also circumcised.
Pope John XXIII changed the liturgical emphasis of Jan. 1 to focus on the Octave of Christmas — which was in keeping with earlier traditions that marked important feasts (like Easter) for eight days. In 1969, Pope Paul VI made it the feast of Mary, the Mother of God, a holy day of obligation. World Day of Peace on Jan. 1 has also been marked by a papal message every year since 1967.
Why all the different emphases?
Mostly because the calendar itself, both religious and secular, has changed a lot.
In Jewish tradition, the new year, called Rosh Hashanah (meaning First of the Year), is in September. However, the first month of the Jewish year is Nisan, which takes place in March or April, when Passover occurs.
For ancient Romans, the New Year began in March, close to the spring equinox. We can still see this history in some of the names of our own months, taken from the Latin; while September, October, November and December mean the 7th, 8th, 9th and 10th months in Latin, they are actually our ninth through 12th months. However, for Roman governmental purposes from the second century B.C., the Roman year began in January, when the counsels (government leaders) took office.
In 45 B.C., Julius Caesar undertook a major revision of the calendar. (This is why the Orthodox churches still uses what is called the revised Julian calendar.) He set Jan. 1 as the official start of the calendar year, though the new year kept being celebrated in March with spring rituals. Still, just before Jan. 1, Romans were also celebrating a mid-winter feast called the Saturnalia, when they exchanged presents and took part in orgies and general foolishness, so Julius’ changes fit right in.
Christianity at first had nothing to do with the new year, since the central feast of the church was (and remains) the Resurrection, or Easter. Gradually, however, the celebration of the birth of Christ entered the church calendar and, by the fifth century, celebrating the Nativity feast was becoming common in church communities across Europe. (In the Eastern church, the feast of the Epiphany on Jan. 6 was, and is, the main feast.)
With the date of Christmas being set on Dec. 25, which seems to have first happened in Rome around the late 4th century, the feasts of the Circumcision and the Holy Name could be set on Jan. 1. (This also set the date for the feasts of the Annunciation on March 25 and the Birth of John the Baptist on June 24.)
However, Jan. 1 was not the New Year for most of Europe for many centuries. This was largely because Christian Europe was concerned about the holdover of celebrations from pagan holidays, and because the Roman custom of marking the new year in March continued.
Other New Year’s Day dates, noted by the Catholic Encyclopedia, included March 25 (the Annunciation) in England, Easter in Germany and Sept. 1 in Russia. In fact, British countries — including the American colonies — did not adopt Jan. 1 as the start of the new year until 1752.
Since the celebration of Advent begins the church year — a practice that started around the 6th century and settled into its now familiar pattern of four weeks by the time of Pope St. Gregory VII in the late 11th century — a secular New Year was largely incidental.
However, most countries in the West settled on Jan. 1 as New Year’s Day, thanks to Pope Gregory XIII, 500 years later. (Which is why our calendar is called the Gregorian calendar in the West.)
The Julian calendar of Julius Caesar had worked pretty well over the centuries. But because it did not contain an accurate leap year – to adjust for the fact that a solar year is not 365.25 days long (as Julius decreed) but 365.242 days, the calendar was out of whack with real time by the 16th century. In fact, it made the spring equinox fall on March 14 instead of March 25.
So Pope Gregory gathered the astronomical experts of his day and readjusted the calendar. This actually entailed eliminating 10 days from the month of October in 1582 to reset things. The pope also set the first day of the year as Jan. 1. Which, as already noted, took a while to catch on in many countries.
Sources: www.Jewishvirtuallibrary; Catholic Encyclopedia; Modern Catholic Encyclopedia; The Harper Collins Encyclopedia of Catholicism; The Dictionary of the Liturgy.