The Feast of the Circumcision of Christ is a Christian celebration of the circumcision of Jesus in accordance with Jewish tradition, eight days (according to the Semitic and southern European calculation of intervals of days) after his birth, the occasion on which the child was formally given his name.
The circumcision of Jesus has traditionally been seen as the first time the blood of Christ was shed, and thus the beginning of the process of the redemption of man, and a demonstration that Christ was fully human, and of his obedience to Biblical law.
The feast day appears on 1 January in the liturgical calendar of the Byzantine Catholic and Eastern Orthodox churches. In the General Roman Calendar, the 1 January feast, which from 1568 to 1960 was called “The Circumcision of the Lord and the Octave of the Nativity”, is now named the Solemnity of Mary, Mother of God, and the Octave Day of the Nativity of the Lord. It is celebrated by some churches of the Anglican Communion and virtually all Lutheran churches. In these latter Western Christian denominations, the Feast of the Naming and Circumcision of Jesus Christ marks the eighth day (octave day) of Christmastide.
Picture from the Menologion of Basil II