St. Matthew, one of the twelve Apostles, is the author of the first Gospel. This has been the constant tradition of the Church and is confirmed by the Gospel itself. He was the son of Alpheus and was called to be an Apostle while sitting in the tax collectors place at Capernaum. Before his conversion he was a publican, i.e., a tax collector by profession. He is to be identified with the "Levi" of Mark and Luke.

His apostolic activity was at first restricted to the communities of Palestine. Nothing definite is known about his later life. There is a tradition that points to Ethiopia as his field of labor; other traditions mention of Parthia and Persia. It is uncertain whether he died a natural death or received the crown of martyrdom.

St. Matthew's Gospel was written to fill a sorely-felt want for his fellow countrymen, both believers and unbelievers. For the former, it served as a token of his regard and as an encouragement in the trial to come, especially the danger of falling back to Judaism; for the latter, it was designed to convince them that the Messiah had come in the person of Jesus, our Lord, in Whom all the promises of the Messianic Kingdom embracing all people had been fulfilled in a spiritual rather than in a carnal way: "My Kingdom is not of this world." His Gospel, then, answered the question put by the disciples of St. John the Baptist, "Are You He Who is to come, or shall we look for another?"

Writing for his countrymen of Palestine, St. Matthew composed his Gospel in his native Aramaic, the "Hebrew tongue" mentioned in the Gospel and the Acts of the Apostles. Soon afterward, about the time of the persecution of Herod Agrippa I in 42 AD, he took his departure for other lands. Another tradition places the composition of his Gospel either between the time of this departure and the Council of Jerusalem, i.e., between 42 AD and 50 AD or even later. Definitely, however, the Gospel, depicting the Holy City with its altar and temple as still existing, and without any reference to the fulfillment of our Lord's prophecy, shows that it was written before the destruction of the city by the Romans in 70 AD, and this internal evidence confirms the early traditions.