From Ignatius of Antioch

Let us not be insensible of Christ's loving kindness. For if he had acted as we do, we would have been lost indeed. Therefore let us become his disciples and learn to live in the Christian way; those who are called by any other name are not of God. Cast out the evil leaven that has become old and sour, and replace it with the new leaven, which is Jesus Christ. He must be the salt of your lives, so that none of you may become corrupt, since it is by your wholesomeness that you will be judged.

I do not write this to you, my dear friends, because I have heard that any one of you is thus disaffected, but because, though I am less than yourselves, I would have you all guard against falling into the snares of false doctrine. Have a firm faith in the reality of the Lord's birth and passion and resurrection which took place when Pontius Pilate was procurator. All these deeds were truly and certainly accomplished by Jesus Christ, who is our hope; my none of you ever be turned away from him! [Letter to the Magnesians, 10-11]