We don’t really know much about St. Matthias. We have no idea the qualifications that led to his being nominated as one of two possibilities to take Judas’s position among the Twelve Apostles. But clearly, they would have nominated a holy and faithful man, and then they left the deciding up to the Holy Spirit. Praying, they cast lots, and the lots selected Matthias, who then became one of the Twelve. He is not mentioned anywhere else in the New Testament, so we don’t know much about his ministry.
What is striking about the selection of St. Matthias though is that this is the first of the disciples or Apostles that was not selected directly by Jesus. Jesus selected all of the original Twelve, but Matthias is the first to be selected by the fledgling Church on the authority passed on by Jesus himself. They act not on their own, but on the authority of Jesus, being led by the Holy Spirit for the glory of God the Father.
A similar process has been repeated through the ages, over and over again, to select men to be popes, bishops, priests and deacons, and men and women for religious communities. The process begins with prayer and ends with thanksgiving and glory to God. People propose the candidates as being noted for holiness and ability, but it is God who makes the final choice.
Today we praise God for the Twelve Apostles, of which Matthias was one. We praise God for the authority of the Apostles which has echoed through the ages giving guidance to the Church. We praise God for the gift of the Holy Spirit who is active in all our decision making.