Advent’s third Sunday is called “Gaudete” Sunday, which translates as “rejoice”. Beginning in the 13th century, Catholic priests began the third Sunday in Advent’s liturgy with a Latin introit that read, “Rejoice (i.e., “Gaudete”) in the Lord always, and again I say rejoice.” The Church reasoned, how could a Sunday that begins with an inducement to “rejoice” be enshrouded by somber purple? For this reason the vestments for this Sunday are colored rose, a lighter shade of purple (they are not pink, a lighter shade of red). The rose vestments represent a softening of the penitential season. Gaudete Sunday is the “half time” for Advent - a time for taking a deep breath in the midst of our preparation for Christ’s coming. Lutheran churches use blue vestments during Advent to suggest expectant hope. One reason for this choice was that in former times, purple dye was quite expensive. In addition, some Lutheran churches felt that although the penitential nature of purple was appropriate for Lent with its pilgrimage to Christ’s suffering on the cross, they questioned whether penitence (even if fueled by Advent’s overtones of “judgement”) should be the primary theme for Advent in preparation for Christ’s birth.
~Dr. Gil Haas, St. Augustine of Canterbury Episcopal Church