74 And why, my, opponent says, did God, the Ruler and Lord of the universe, determine that a Saviour, Christ, should be sent to you from the heights of heaven a few hours ago, as it is said? We ask you too, on the other hand, what cause, what reason is there that the seasons sometimes do not recur at their own months, but that winter, summer, and autumn come too late? Why, after the crops have been dried up and the grain has perished, showers sometimes fall which should have dropped on them while yet uninjured, and made provision for the wants of the time?
Nay, this we rather ask, why, if it were fitting that Hercules should be born, Aesculapius, Mercury, Liber, and some others, that they might be both added to the assemblies of the gods, and might do men some service—why they were produced so late by Jupiter, that only later ages should know them, while the past ages of those who went before knew them not? You will say that there was some reason. There was then some reason here also that the Saviour of our race came not lately, but today.
What, then, you ask, is the reason? We do not deny that we do not know. For it is not within the power of any one to see the mind of God, or the way in which He has arranged His plans. Man, a blind creature, and not knowing himself even, can in no way learn what should happen, when, or what its nature is: the Father Himself, the Governor and Lord of all, alone knows. Nor, if I have been unable to disclose to you the causes why something is done in this way or that, does it straightway follow, that what has been done becomes not done, and that a thing becomes incredible, which has been shown to be beyond doubt by such virtues and powers.
Source: Against the Heathen (New Advent)