Father, Son and Spirit are worshiped and adored

But both Him, and the Son who came forth from Him and taught us these things, and the host of the other good angels who follow and are made like to Him, and the prophetic Spirit, we worship and adore, knowing them in reason and truth, and declaring without grudging to every one who wishes to learn, as we have been taught.

Justin Martyr
First Apology
Chapter VI

The Cross as T-shaped.

For the Scripture saith, “And Abraham circumcised ten, and eight, and three hundred men of his household.” What, then, was the knowledge given to him in this? Learn the eighteen first, and then the three hundred. The ten and the eight are thus denoted—Ten by Ι, and Eight by Η. You have the initials of the, name of Jesus. And because the cross was to express the grace of our redemption by the letter Τ, he says also, “Three Hundred.” He signifies, therefore, Jesus by two letters, and the cross by one.

Epistle of Barnabus
Chapter IX

The Resurrection is both physical and spiritual

I salute your most worthy bishop, and your very venerable presbytery, and your deacons, my fellow-servants, and all of you individually, as well as generally, in the name of Jesus Christ, and in His flesh and blood, in His passion and resurrection, both corporeal and spiritual, in union with God and you. Grace, mercy, peace, and patience, be with you for evermore!

Ignatius of Antioch
Epistle to the Smyrneans
Chapter XII

Heretics do not accept the Eucharist as Real Presence

Do ye, therefore, notice those who preach other doctrines, how they affirm that the Father of Christ cannot be known, and how they exhibit enmity and deceit in their dealings with one another. They have no regard for love; they despise the good things we expect hereafter; they regard present things as if they were durable; they ridicule him that is in affliction; they laugh at him that is in bonds.

They abstain from the Eucharist and from prayer, because they confess not the Eucharist to be the flesh of our Savior Jesus Christ, which suffered for our sins, and which the Father, of His goodness, raised up again.

Ignatius of Antioch
Epistle to the Smyrneans
Chapter VI-VII