Epistle to Diognetus
The Epistle to Diognetus
The epistle Diognetus, in the Ante-Nicene Fathers, is ascribed to Mathetes, a Christian apologist writing to a gentile who is interested in the beliefs of the Christians. Due to its style and content is is often dated in the early second century, and hence in the second book in ANF01.

Images and superstition
Contrasting Christians with Pagans and Jews, Mathetes draws out two differences in the style of worship of the early Christians and the religious world which surrounded them.
Images
Mathetes continues the Old Testament critique of the use of images in worship. How can you take a block of wood or stone or metal, form one part into an idol worthy of worship, and form another part into a table or a brick or a tool? With one piece of wood you cook and warm yourself, and with another you bow down and worship. If the wood is worthy of worship, why do you burn it to warm you up; if it's just to be burned to keep you warm, why do you bow down and worship it?
Isaiah (44:18-20) writes:
They know not, nor do they discern, for he has shut their eyes, so that they cannot see, and their hearts, so that they cannot understand. No one considers, nor is there knowledge or discernment to say, “Half of it I burned in the fire; I also baked bread on its coals; I roasted meat and have eaten. And shall I make the rest of it an abomination? Shall I fall down before a block of wood?” He feeds on ashes; a deluded heart has led him astray, and he cannot deliver himself or say, “Is there not a lie in my right hand?”
And Mathetes writes:
Might not these, which are now worshipped by you, again be made by men vessels similar to others? Are they not all deaf? Are they not blind? Are they not without life? Are they not destitute of feeling? Are they not incapable of motion? Are they not all liable to rot? Are they not all corruptible? These things ye call gods; these ye serve; these ye worship; and ye become altogether like to them. For this reason ye hate the Christians, because they do not deem these to be gods. But do not ye yourselves, who now think and suppose [such to be gods], much more cast contempt upon them than they [the Christians do]?
It's also no use claiming that you are actually worshipping the deity which is represented by or is behind the idol. If this deity is truly alive, isn't it offensive to them that you present to them blood and smoke? Would you enjoy someone slaughtering animals and burning them so that the smoke rose into your face and you breathed in the smell? Obviously not - because you have sense. So if these idols have sense, why do the same to them?
And by those gifts which ye mean to present to them, do ye not, if they are possessed of sense, rather punish [than honour] them? But if, on the other hand, they are destitute of sense, ye convict them of this fact, while ye worship them with blood and the smoke of sacrifices. Let any one of you suffer such indignities! Let any one of you endure to have such things done to himself! But not a single human being will, unless compelled to it, endure such treatment, since he is endowed with sense and reason.
I think this is important evidence for the absence of idols, images, statues or icons in early Christian worship. If there was, we would expect Mathetes at this point to present a reason why this does not apply for the images seen in Christian worship. Instead, he is silent on the matter of images in Christian worship, it does seem like they were absent for early Christian worship.
Superstition
Against the Jews of his day Mathetes contrast their superstition with Christian beliefs. The Jews are scrupulous to watch for the right days and months, to do things with the approval of the stars. They view some days as spiritually special and others as normal. Some days are good for festivities, others for mourning.
And as to their observing months and days, as if waiting upon the stars and the moon, and their distributing, according to their own tendencies, the appointments of God, and the vicissitudes of the seasons, some for festivities, and others for mourning,—who would deem this a part of divine worship, and not much rather a manifestation of folly?
Yet to Paul, these are one a shadow of the things to come. Colossians 2:16-17
Therefore let no one pass judgment on you in questions of food and drink, or with regard to a festival or a new moon or a Sabbath. These are a shadow of the things to come, but the substance belongs to Christ.
Some people today say that the Protestant Reformation is to blame for the disenchantment in the West. Yet Christians have always opposed superstition and taught that we should not put too much stock in these 'shadows that are passing away'. In general, we need to be sober minded and rational, offering praise to the true God and living in the true world, not following an imaginary world of rules regarding days and weeks.
I say this without commenting on the place of saint's days in the church calendar, without commenting on the deeper meaning of magical and mythical stories, and without commenting on the place of the Sabbath in the Christian life. They are all topics too big to be discussed here. At the very least, I will say that however we use them, we never let supersition and superstitious behaviour take root.
Knowledge and Life
Mathetes has an interesting discussion at the end of his work about knowledge and life. He argues that life and knowledge always go together, they are intimately connected. God showed this in Genesis when He planted the tree of knowledge of Good and Evil and the tree of Life in the garden of Eden. Yet the cause of the fall was disobedience, not knowledge.
For in this place the tree of knowledge and the tree of life have been planted; but it is not the tree of knowledge that destroys— it is disobedience that proves destructive.
Therefore, if we are to be restored we need true knowledge, not false knowledge, for:
For he who thinks he knows anything without true knowledge, and such as is witnessed to by life, knows nothing, but is deceived by the Serpent, as not loving life. But he who combines knowledge with fear, and seeks after life, plants in hope, looking for fruit. Let your heart be your wisdom; and let your life be true knowledge inwardly received.
Therefore, we must get the true knowledge of God the Father and the Son
If you also desire [to possess] this faith, you likewise shall receive first of all the knowledge of the Father.
It is true knowledge which is the start of the redemption of a person. Therefore, we must seek out the truth. We must replace the lies we believe about God and the world with true things, revealed by God and discovered in the world.