Ignatius on Philippians 4:13 in His Letter to Smyrna around 105CE

I give you these instructions, beloved, assured that you also hold the same opinions [as I do]. But I guard you beforehand from these beasts in the shape of men, from whom you must not only turn away, but even flee from. Only you must pray for them, if by any means they may be brought to repentance. For if the Lord were in the body in appearance only, and were crucified in appearance only, then am I also bound in appearance only. And why have I also surrendered myself to death, to fire, to the sword, to the wild beasts? But, [in fact,] I endure all things for Christ, not in appearance only, but in reality, that I may suffer together with Him, while He Himself inwardly strengthens me; for of myself I have no such ability.

Some have ignorantly denied Him, and advocate falsehood rather than the truth. These persons neither have the prophecies persuaded, nor the law of Moses, nor the Gospel even to this day, nor the sufferings we have individually endured. For they think also the same thing regarding us. For what does it profit, if any one commends me, but blasphemes my Lord, not owning Him to be God incarnate? He that does not confess this, has in fact altogether denied Him, being enveloped in death. I have not, however, thought good to write the names of such persons, inasmuch as they are unbelievers; and far be it from me to make any mention of them, until they repent.

Let no man deceive himself. Unless he believes that Christ Jesus has lived in the flesh, and shall confess His cross and passion, and the blood which He shed for the salvation of the world, he shall not obtain eternal life, whether he be a king, or a priest, or a ruler, or a private person, a master or a servant, a man or a woman. “He that is able to receive it, let him receive it.” Let no man’s place, or dignity, or riches, puff him up; and let no man’s low condition or poverty humiliate him. For the chief points are faith towards God, hope towards Christ, the enjoyment of those good things for which we look, and love towards God and our neighbor. For, “You shall love the Lord thy God with all your heart, and your neighbor as yourself.”

And the Lord says, “This is life eternal, to know the only true God, and Jesus Christ whom He has sent.” And again, “A new commandment give I unto you, that you love one another.” … Do you, 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.