The Epistle to Diogentus

Since I perceive, most excellent Diognetus, that you are exceedingly zealous to learn the religion of the Christians and are asking very clear and careful questions concerning them, both who is the God in whom they believe, and how they worship him, so that all disregard the world and despise death, and do not reckon as Gods those who are considered to be so by the Greeks, nor keep the superstition of the Jews, and what is the love which they have for one another, and why this new race or practice has come to life at this time, and not formerly; I indeed welcome this zeal in you, and I ask from God who bestows on us the power both of speaking and of hearing, that it may be granted to me so to speak that you may benefit so much as possible by your hearing, and to you so to hear that I may not be made sorry for my speech.

Come then, clear yourself of all the prejudice which occupies your mind, and throw aside the custom which deceives you, and become as it were a new man from the beginning, as one, as you yourself also admitted, who is about to listen to a new story. Look, not only with your eyes, but also with your intelligence, what substance or form they chance to have whom you call gods and regard as such.