John was called "Chrysostom" ("Golden Mouth") because of his eloquence. He was a priest of Antioch, and an outstanding preacher. (Audiences were warned not to carry large sums of money when they went to hear him speak, since pickpockets found it very easy to rob his hearers -- they were too intent on his words to notice what was happening.) His sermons are mostly straightforward expositions of Holy Scripture (he has extensive commentaries on both Testaments, with special attention to the Epistles of Paul), and he emphasizes the literal meaning, whereas the style popular at Alexandria tended to read allegorical meanings into the text.
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, and 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.
Along with Athanasius of Alexandria, Basil the Great, and Gregory of Nazianzus, he is counted as one of the Four Great Eastern (or Greek) Doctors of the Ancient Church. The Four Great Western (or Latin) Doctors are Ambrose, Jerome, Augustine, and Gregory the Great.
Propers for St. John Chrysostom - Bishop of Constantinople, Preacher, Theologian and Liturgist
O GOD, who didst give grace to thy servant John, eloquently to declare thy righteousness in the great congregation, and fearlessly to bear reproach for the honour of thy Name: Mercifully grant unto all bishops and pastors such excellency in preaching, and fidelity in ministering thy Word, that thy people may be partakers with them of the glory that shall be revealed; through Jesus Christ our Lord. Amen.
The Epistle - Jeremiah 1:4-9.
THE word of the LORD came unto me, saying, Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee, and I ordained thee a prophet unto the nations. Then said I, Ah, LORD God! behold, I cannot speak: for I am a child. But the LORD said unto me, Say not, I am a child: for thou shalt go to all that I shall send thee, and whatsoever I command thee thou shalt speak. Be not afraid of their faces: for I am with thee to deliver thee, saith the LORD. Then the LORD put forth his hand, and touched my mouth. And the Lord said unto me, Behold, I have put my words in thy mouth.
The Gospel - St. Luke 21:12-15.
But before all these, they shall lay their hands on you, and persecute you, delivering you up to the synagogues, and into prisons, being brought before kings and rulers for my name's sake. And it shall turn to you for a testimony. Settle it therefore in your hearts, not to meditate before what ye shall answer: For I will give you a mouth and wisdom, which all your adversaries shall not be able to gainsay nor resist.
Reference and Resources: