"It would seem there there was ignorance in Christ," St Thomas says (ST III.15.3), because ignorance is basic to what it means to be human, and because he "knew no sin,"and because the prophecy of the virgin birth (Isa 8.4) declared that the child Christ would have to learn to call his father or his mother by name. "On the contrary," Aquinas counters, Jesus is full of knowledge, just as he is full of grace and virtue. He must be: he is God!
At the beginning of the section in question (ST III.9.1), Aquinas takes pains to explain why it is that Christ needed to know as we know (or at least as we would know if we were true to ourselves): "It was fitting that the Son of God should assume, not an imperfect, but a perfect human nature, since the whole human race was to be brought back to perfection by its means." Jesus, in other words, assumes for our sake our nature in its fulness, and in that assumption knows divinely and humanly—but not at all sinfully. He not only knew the Father most perfectly, he also knew the mysteries of the incarnation more fully than anyone else. And he needed to know all things, and to know them fully in their fulness, because anything less would mean our doom, our undoing.
Needless to say, St Thomas knows that the young Christ is said to have asked questions of the teachers in the Temple, and to have grown in wisdom as well as stature (Lk 2.46,52). He knows that Jesus is said to have "learned obedience through the things that he suffered" (Heb. 5.8). And he knows that Jesus himself said no one knows the timing of the end, "not even the angels in heaven, nor the Son, but only the Father" (Mt 24.36). Bearing all that in mind, Aquinas insists first on the distinction between divine and human knowledge, and then on the distinction between knowledge that is infused by grace and knowledge that is acquired by experience. On the basis of those distinctions, he argues that as Christ matured, submitting to the wisdom of his mother and Joseph, he learned in one way what he already knew in another (ST III.12.2).
So, why did Christ ask questions, then? Why submit to learning? Why yield to the experience of suffering? And why, at the end of his life, did he claim not to know "the day or the hour" of his own appearing?
Answering the first questions, St Thomas (ST III.12.3) appeals to Origen's teaching: "Our Lord asked questions not in order to learn anything, but in order to teach by questioning. For from the same well of knowledge came the question and the wise reply." And offers his own agreement: "Jesus advanced in empiric knowledge, as in age... As a fitting age is required for a man to acquire knowledge by discovery, so also that he may acquire it by being taught. But our Lord did nothing unbecoming to his age."
Answering the last question, he offers a few possible resolutions. Perhaps Jesus is speaking not of himself but of his body, the church, or about the adopted sons of God. Or perhaps he's simply refusing to make known to the apostles what he in truth knows. In any case, St Thomas is adamant that if the Son knows that the Father knows, then he necessarily knows what the Father knows. For our sake, however—and only for our sake—he decides to accommodate that knowing to how we know. So, he concludes, this strange saying is best understood as a reference to the apostles' lack of readiness for the truth, not to any ignorance on Jesus' part.
In one of his sermons, exulting at the wonder that Jesus, who is the truth, grows in wisdom, Thomas contends that Jesus' intellectual growth is simply the working out of what is always already his. Jesus' soul, at its deepest depths, was from the moment of conception filled with every grace and truth. But he wisely and graciously did not reveal this fulness too soon: "He wished to reveal his wisdom little by little, not all at once, so that the truth of his human nature within him would be accepted, and so that he might give us an example of growing in wisdom." As with everything he said and did, Jesus' learned in ways that taught us the truth.
This, it seems to me, is the bottom line, which explains why St Thomas had to say what he said: insofar as ignorance is a moral fault, or a condition that threatens the good of others, Jesus cannot have been ignorant. Not if we’re going to say he did not sin. Not if we’re going to say he did not cause others to sin. If Jesus is always did good, and the best good that could be done, not for himself but for all, then he had to have the knowledge necessary to live so wisely. As St Thomas says, "ignorance does not drive out ignorance." And to say the same thing another way, ignorance cannot be a revelation of knowledge. So, if Jesus is, as we confess, the one who reveals the truth of both created being and the uncreated life that is beyond being, then he cannot be unknowing or clueless or naive or uninformed.
All that said, I do think we can say more, even if it's only shading or etching.
Jesus not only did not exploit his relationship with his Father (Phil. 2.6), he also did not abuse himself or in any sense indulge his own "powers"—including his own knowledge. He knew the Father's will perfectly, of course, which necessarily means that he in some sense recognized what must unfold in the present and into his future. But he never allowed anticipation to unsettle or disturb him. The Gospels make it clear that he lived with an awareness of the sorrow that awaited him at the end of his life. But they also make it clear that he did not give himself to the sorrowing until the time came for it in the garden. The same was true for every moment of his life, every experience, every encounter.
We cannot overemphasize the wonder of this truth: Jesus did not grasp for knowledge out of its time. Just as he did not anticipate, he did not speculate; always learning, always attentive, he was never vainly curious, never nosy or inquisitorial. He was happy to let knowledge come to him when it was time for it to come. All to say, then, when Jesus tells the apostles that no one knows about the End, he's telling them that they do not need to know what they think they need to know. And more than that, he's telling them that all they actually need to know is him. What matters is not some event in the future, a so-called "second coming," imagined as a point on the timeline of history, but the Son himself. The "appearing" of the Son is something that happens not in time but to it, affecting and transfiguring every point on the timeline at once. Just so, there cannot be a true knowing of the Son in his fullness that doesn’t essentially change the way that we know. As the Scripture says, "When Christ appears, we shall be like him, for we shall see him as he is" (1 Jn 3.2).
In some sense, we do await the consummation of the ages, the taking of all creation, as a whole, into the triune life, so that creation in its fulness is at every depth entirely energized by God's own liveliness. "Hope that is seen is not hope." Strictly speaking, however, that End is in my past as well as my future, because the God who is my life in its fulness is already present, already "at hand"—and he has been from the foundations of the world, because he has been raised from the dead as creation's true beginning and end. This is why Scripture insists at every turn that"today is the day of salvation" (2 Cor. 6.2). The appearing of the Son of Man is happening now, not then—if only we do not harden our hearts (Heb. 3.7), if only we are willing to learn a new knowledge and a new way of knowing from what cannot but seem, at first, to be his ignorance.