My very best wishes to all my readers for a very happy 2013!
Historically, the Church commemorated Jesus’s circumcision on this day.
Since the Renaissance (specifically, the papacy of Pius V), the Catholic Church has designated this day as the Solemnity of Mary the Mother of God.
It was usual for, if not mandated that, Christians attend church on New Year’s Day as a refusal to descend into the pagan revelry associated with the New Year. Penance and fasting were also part of the commemoration of this day in the early Church.