Among the early followers and apostles of Jesus, Matthew is mentioned in Matthew 9:9 and Matthew 10:3 as a tax collector who, while sitting at the “receipt of custom” in Capernaum, was called to follow Jesus:
As Jesus passed on from there, he saw a man named Matthew sitting at the customs post. He said to him, “Follow me.” And he got up and followed him. While he was at table in his house, many tax collectors and sinners came and sat with Jesus and his disciples. The Pharisees saw this and said to his disciples, “Why does your teacher eat with tax collectors and sinners?” He heard this and said, “Those who are well do not need a physician, but the sick do. Go and learn the meaning of the words, ‘I desire mercy, not sacrifice. I did not come to call the righteous but sinners.”
Jesus never officially equates taxation with theft, He clearly equates tax collectors with sinners.
But, while Matthew indeed was a corrupt, sinful tax collector, the New Testament records that he converted and became one of the most important Apostles. As a disciple, he followed Jesus, and was one of the witnesses of the Resurrection and the Ascension of Jesus. Later Church fathers such as Irenaeus (Against Heresies 3.1.1) and Clement of Alexandria claim that Matthew preached the Gospel to the Jewish community in Judea, before going to other countries. Ancient writers are not agreed as to what these other countries are.
He is also likely the author of the Gospel of Matthew, though the Gospel is officially anonymous.
It should be made clear that St. Matthew gave up his sinful tax collection when he followed Jesus.
Picking a reviled tax collector was just another controversial act by Jesus Christ, but it was a bold statement setting the standard for his ministry. He came down from Heaven to convert sinners, corrupt tax collectors being the prime candidates. This should give hope to all those statist Catholics and Christians who defend unjust government. They too can repent of their ways and follow Christ!