John was called Chrysostom (which means "Golden Mouth") because of his eloquence. He was a priest of Antioch known as an outstanding preacher. So much so that congregations were warned not to carry large sums of money when they went to hear him speak, since pickpockets found it easy to rob his listeners as they were too intent on his words to notice. His sermons were mostly unadorned expositions of Holy Scripture emphasizing literal meaning, even though the style in Alexandria in his day tended to the allegorical.
He loved the city and people of Antioch and they loved him. However, he became so famous that the Empress at Constantinople decided that she must have him for her court preacher, so she had him kidnapped and brought to Constantinople and there made bishop.* This was a failure all around. His sermons against corruption in high places earned him powerful enemies (including the Empress), and he was sent into exile, where he died in the year 407.
O God, you gave your servant John Chrysostom grace eloquently to proclaim your righteousness in the great congregation, and fearlessly to bear reproach for the honor of your Name: Mercifully grant to all bishops and pastors such excellence in preaching, and faithfulness in ministering your Word, that your people may be partakers with them of the glory that shall be revealed; through Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, one God, for ever and ever. Amen.
[*Yes, he had to be kidnapped to be made a bishop, so reluctant was he for the office. This may mean that he is the one person in Christian history who actually should have been a bishop.]