Why do we celebrate the Solemnity of St. Joseph?
In his Apostolic Exhortation Custodian of the Redeemer, Pope St. John Paul II elaborates on this statement of Pope Leo XIII, as it touches upon Mary and Joseph’s vocation with respect to the Incarnation of the Eternal Word, [This is] the mystery in which Joseph of Nazareth “shared” like no other human being except Mary, the Mother of the Incarnate Word. He shared in it with her; he was involved in the same salvific event; he was the guardian of the same love, through the power of which the eternal Father “destined us to be his sons through Jesus Christ” (Eph 1:5). And later, [If] Mary is the Lord’s humble servant, prepared from eternity for the task of being the Mother of God. Joseph is the one whom God chose to be the “overseer of the Lord’s birth”, the one who has the responsibility to look after the Son of God’s “ordained” entry into the world, in accordance with divine dispositions and human laws (Custodian of the Redeemer, 8).
The Church therefore honors St. Joseph on Match 19th for his faithfulness to God, and to his vocation as Custodian of the Redeemer.