The epistles of Ignatius, most probably written on his path to martyrdom, sound in a lot of ways like the epistles of Paul. He opens with loving greetings, he gives praise to the believers he writes to. He has a theme in his writings of calling for unity. And this call for unity is centered on being subject to your bishop as you would be subject to Christ.
“For we ought to receive everyone to whom the master of the house sends to be over his household, as we would do Him that sent him.”
Ignatius says that anyone who doesn’t worship under the hierarchy of the God’s appointed bishops cuts himself off from the church. Also “any activity or service that takes place without either his [the bishop’s] presence or permission has no validity”:
He, therefore, that does not assemble with the Church, has even by this manifested his pride, and condemned himself. For it is written, “God resisteth the proud.” (Pro_3:34; Jam_4:6; 1Pe_5:5) Let us be careful, then, not to set ourselves in opposition to the bishop, in order that we may be subject to God.
It is not lawful without the bishop either to baptize or to celebrate a love-feast; but whatsoever he shall approve of, that is also pleasing to God, so that everything that is done may be secure and valid.
The above concepts are also part of the start of the Catholic movement, discussed in II.0 The Catholic Movement. This represents a major shift from the loose confederation of fellowships that most agree is the picture painted in Acts and the Epistles. Ignatius’ emphasis on the authority and structure of church government is beyond anything previously written. Ignatius makes the first reference to the Catholic Church in this focus of his on the authority of the bishop:
Wherever the bishop shall appear, there let the multitude [of the people] also be; even as, wherever Jesus Christ is, there is the Catholic (Emphasis added) Church.
Ignatius’ emphasis is reasonable, but we must always remember that just because it is reasonable it isn’t right, or what God chose. Solomon wrote, ” Every way of a man is right in his own eyes; But Jehovah weigheth the hearts. [Pro 21:2]
One other major theme is present in the epistles of Ignatius, that of martyrdom. Ignatius wrote his epistles on his way to be martyred. As the views of Ignatius concerning martyrdom them are unusual in some ways, that is the subject of the next article.
 Introductory Note to the Epistle of Ignatius to the Ephesians, Chap. VI. — Have Respect to the Bishop as to Christ Himself, E-Sword Program
 THE APOSTOLIC FATHERS, edited by Michael W. Holmes, Baker Books, Grand Rapids, 1999, p. 129
 The Epistle of Ignatius to the Ephesians, Chap. V. — The Praise of Unity, E-Sword Program
 The Epistle of Ignatius to the Smyrnaeans, Chap. VIII. — Let Nothing Be Done Without the Bishop. , E-Sword Program