The Didache (Church history)
This is a document from the earliest decades of the Christian Church, and is entitled the Teaching of the Lord by the Apostles to the Nations, usually referred to these days as the Teaching or, in its Greek form, the Didache. The value of the document, which is dated to the first century AD (the Apostolic age, so contemporary or almost contemporary with the books of the New Testament), is their evidence of Christian teaching beyond Holy Scripture. It may be described as a catechism, which certainly have been formed by one or more of the Apostles or their associates. Learn more about the document at the Wikipedia page, and discover the full length of it here. It is not terribly long, but only snippets will be copied-and-pasted here from the last link. It is fascinating...
"...of these sayings the teaching is this: Bless those who curse you, and pray for your enemies, and fast for those who persecute you. For what reward is there for loving those who love you? Do not the Gentiles do the same? But love those who hate you, and you shall not have an enemy. Abstain from fleshly and worldly lusts. If someone strikes your right cheek, turn to him the other also, and you shall be perfect."
"You shall not take evil counsel against your neighbor. You shall not hate any man; but some you shall reprove, and concerning some you shall pray, and some you shall love more than your own life."
"Rather, be meek, since the meek shall inherit the earth. Be long-suffering and pitiful and guileless and gentle and good and always trembling at the words which you have heard... Accept whatever happens to you as good, knowing that apart from God nothing comes to pass."
"And concerning baptism, baptize this way: Having first said all these things, baptize into the name of the Father, and of the Son, and of the Holy Spirit, in living water. But if you have no living water, baptize into other water; and if you cannot do so in cold water, do so in warm. But if you have neither, pour out water three times upon the head..."
"...every Lord's day gather yourselves together, and break bread, and give thanksgiving after having confessed your transgressions, that your sacrifice may be pure. But let no one who is at odds with his fellow come together with you, until they be reconciled, that your sacrifice may not be profaned."
"Appoint, therefore, for yourselves, bishops and deacons worthy of the Lord, men meek, and not lovers of money, and truthful and proved; for they also render to you the service of prophets and teachers. Therefore do not despise them, for they are your honored ones, together with the prophets and teachers."
"Watch for your life's sake. Let not your lamps be quenched, nor your loins unloosed; but be ready, for you know not the hour in which our Lord will come. But come together often, seeking the things which are befitting to your souls: for the whole time of your faith will not profit you, if you are not made perfect in the last time."
There is more, naturally, so visit the link and read the whole. This is the kind of catechism you can fold up quickly and stuff into your toga.