55 But when, overcome, we agree that there are these things, and expressly allow that all human affairs are full of them, they will next ask, Why, then, the Almighty God does not take away these evils, but suffers them to exist and to go on without ceasing through all the ages? If we have learned of God the Supreme Ruler, and have resolved not to wander in a maze of impious and mad conjectures, we must answer that we do not know these things, and have never sought and striven to know things which could be grasped by no powers which we have, and that we, even thinking it preferable, rather remain in ignorance and want of knowledge than say that without God nothing is made, so that it should be understood that by His will He is at once both the source of evil and the occasion of countless miseries.
Whence then, you will say, are all these evils? From the elements, say the wise, and from their dissimilarity; but how it is possible that things which have not feeling and judgment should be held to be wicked or criminal; or that he should not rather be wicked and criminal, who, to bring about some result, took what was afterwards to become very bad and hurtful, — is for them to consider, who make the assertion. What, then, do we say? Whence? There is no necessity that we should answer, for whether we are able to say whence evil springs, or our power fails us, and we are unable, in either case it is a small matter in our opinion; nor do we hold it of much importance either to know or to be ignorant of it, being content to have laid down but one thing—that nothing proceeds from God Supreme which is hurtful and pernicious.
This we are assured of, this we know, on this one truth of knowledge and science we take our stand—that nothing is made by Him except that which is for the well-being of all, which is agreeable, which is very full of love and joy and gladness, which has unbounded and imperishable pleasures, which every one may ask in all his prayers to befall him, and think that otherwise life is pernicious and fatal.
Source: Against the Heathen (New Advent)