14 May - St. Matthias replaced Judas among the Twelve Apostles. Chosen by lot from among those who accompanied Jesus, beginning with John's baptism and until the day he was taken from us (Ascension) (Acts 1, 22), he received the Holy Spirit with the others on the day of Pentecost. Nothing is known of his apostolic activity.

In the first chapter of the Acts of the Apostles it is reported that after the Ascension of Jesus, the apostle Peter, in the midst of a brethren's assembly of about 120 people, proposed that someone should take the place of Judas to become with the others a witness of the resurrection of Christ (Acts 1,22). The new apostle had to be chosen from among those who had accompanied them during all the time that the Lord Jesus walked at our head (Acts 1,21). Two candidates were proposed, Joseph the Righteous One and Matthias, who were chosen by lot, and Matthias was chosen (cf. Acts 1:21-26). Together with the others he received the Holy Spirit on the day of Pentecost (Acts 2, 4ff).