Augustine wrote his De catechizandis rudibus as a help for those who were giving elementary instructions about Christianity to people who had expressed some interest. His outline included, of course, a study of the Scriptures as the story of salvation. At the end of that he thought that prospective Christians should be warned that they will not be exempt from tests caused not only by the opposition of people outside but also, and perhaps even more, by the lives of wicked Christians. From the number of words devoted to the latter, one is tempted to think that Augustine thought the wicked outnumbered the good within the Church. In any case, the text is another clear illustration that he had a very realistic, not at all idealized, notion of the Church.
11. On the completion of this narration, the hope of the resurrection should be set forth, and, so far as the capacity and strength of the hearer will bear it, and so far also as the measure of time at our disposal will allow, we ought to treat our arguments against the vain scoffings of unbelievers on the subject of the resurrection of the body, as well as on that of the future judgment, with its goodness in relation to good people, its severity in relation to wicked people, its truth in relation to all. And after the penalties of the impious have thus been declared with detestation and horror, then the kingdom of the righteous and faithful, and that supernal city and its joy, should form the next themes for our discourse.
At this point, moreover, we ought to equip and animate the weakness of man in withstanding temptations and offenses, whether these emerge without or rise within the church itself; without, as in opposition to Gentiles, or Jews, or heretics; within, on the other hand, as in opposition to the chaff of the Lord’s threshing-floor. It is not meant, however, that we are to dispute against each several type of perverse men, and that all their wrong opinions are to be refuted by set arrays of argumentations: but, in a manner suitable to a limited allowance of time, we ought to show how all this was foretold, and to point out of what service temptations are in the training of the faithful, and what relief there is in the example of the patience of God, who has resolved to permit them even to the end. But, again, while he is being furnished against these (adversaries), whose perverse multitudes fill the churches so far as bodily presence is concerned, the precepts of a Christian and honorable manner of life should also be briefly and befittingly detailed at the same time, to the intent that he may neither allow himself to be easily led astray in this way, by any who are drunkards, greedy, fraudulent, gamblers, adulterers, fornicators, lovers of public spectacles, wearers of unholy charms, sorcerers, astrologers, or diviners practising any sort of vain and wicked arts, and all other parties of a similar character; nor to let himself fancy that any such course may be followed with impunity on his part, simply because he sees many who are called Christians loving these things and engaging themselves with them, and defending them, and recommending them, and actually persuading others to their use. For as to the end which is appointed for those who persist in such a mode of life, and as to the method in which they are to be borne with in the church itself, out of which they are destined to be separated in the end—these are subjects in which the learner ought to be instructed by means of the testimonies of the divine books. He should also, however, be informed beforehand that he will find in the church many good Christians, most genuine citizens of the heavenly Jerusalem, if he sets about being such himself.
And, finally, he must be sedulously warned against letting his hope rest on man. For it is not a matter that can be easily judged by man which person is righteous. And even were this easy to do, still the reason why examples of righteous men are set before us is not that we may be justified by them, but that, as we imitate them, we may understand how we ourselves also are justified by the One who justified them. For the result of this will be something which must merit the highest approval—namely this, that when the person who is hearing us, or rather, who is hearing God by us, has begun to make some progress in moral qualities and in knowledge, and to enter upon the way of Christ with ardor, he will not be so bold as to ascribe the change either to us or to himself; but he will love both himself and us, and whatever other persons he loves as friends, in Him, and for His sake who loved him when he was an enemy, in order that He might justify him and make him a friend.
(Augustine, De catechizandis rudibus, 7, 11)