Trinitarian salutation

We wish you, brethren, all happiness, while you walk according to the doctrine of the Gospel of Jesus Christ; with whom be glory to God the Father and the Holy Spirit, for the salvation of His holy elect, after whose example the blessed Polycarp suffered, following in whose steps may we too be found in the kingdom of Jesus Christ!

Martyrdom of Polycarp
Chapter XXII

Christ is the only one worshipped

… It is neither possible for us ever to forsake Christ, who suffered for the salvation of such as shall be saved throughout the whole world (the blameless one for sinners), nor to worship any other. For Him indeed, as being the Son of God, we adore; but the martyrs, as disciples and followers of the Lord, we worthily love on account of their extraordinary affection towards their own King and Master, of whom may we also be made companions and fellow-disciples!

Martyrdom of Polycarp
Chapter XVII

The Son is the Eternal Word of God

This is He who was from the beginning, who appeared as if new, and was found old, and yet who is ever born afresh in the hearts of the saints. This is He who, being from everlasting, is today called the Son’ through whom the Church is enriched, and grace, widely spread, increases in the saints, furnishing understanding, revealing mysteries, announcing times, rejoicing over the faithful, giving to those that seek, by whom the limits of faith are not broken through, nor the boundaries set by the fathers passed over.

Mathetes
Epistle to Diognetus
Chapter XI

God manifested himself

…no man has either seen Him, or made Him known, but He has revealed Himself. And He has manifested Himself through faith, to which alone it is given to behold God. For God, the Lord and Fashioner of all things, who made all things, and assigned them their several positions, proved Himself not merely a friend of mankind, but also long-suffering in His dealings with them.

Mathetes
Epistle to Diognetus
Chapter VIII

Christ, the Creator of all, was Sent

For, as I said, this was no mere earthly invention which was delivered to them, nor is it a mere human system of opinion, which they judge it right to preserve so carefully, nor has a dispensation of mere human mysteries been committed to them, but truly God Himself, who is almighty, the Creator of all things, and invisible, has sent from heaven, and placed among men, Him who is the truth, and the holy and incomprehensible Word, and has firmly established Him in their hearts. He did not, as one might have imagined, send to men any servant, or angel, or ruler, or any one of those who bear sway over earthly things, or one of those to whom the government of things in the heavens has been entrusted, but the very Creator and Fashioner of all things—by whom He made the heavens—by whom he enclosed the sea within its proper bounds—whose ordinances all the stars faithfully observe—from whom the sun has receive the measure of his daily course to be observed—whom the moon obeys, being commanded to shin in the night, and whom the stars also obey, following the moon in her course; by whom all things have been arranged, and placed within their proper limits, and to whom all are subject—the heavens and the things that are therein, the earth and the things that are therein, the sea and the things that are therein—fire, air, and the abyss—the things which are in the heights, the things which are in the depths, and the things which lie between.

Mathetes
Epistle to Diognetus
Chapter VII

The Holy Spirit Can Speak

Let us therefore, brethren, be of humble mind, laying aside all haughtiness, and pride, and foolishness, and angry feelings; and let us act according to that which is written (for the Holy Spirit saith, “Let not the wise man glory in his wisdom, neither let the mighty man glory in his might, neither let the rich man glory in his riches; but let him that glorieth glory in the Lord, in diligently seeking Him, and doing judgment and righteousness”), being especially mindful of the words of the Lord Jesus which He spake, teaching us meekness and long-suffering.

Clement of Rome
Epistle to the Corinthians
Chapter XIII