“Mary, Did You Know?”—the popular Christmas tune—was originally released in 1991 and sung by Michael English. The (overly?) dramatic song went on to be a cultural phenomenon. Its lyrics ponder the mystery of a human mother giving birth to a baby boy who will eventually calm a storm with his hand and cause the dead to live again. The song asks a series of questions that really boils down to one: Mary, did you know that your baby is God?

If the song has a theological core, it’s teasing out the truth that the finite can’t comprehend the infinite. Through its questioning, listeners are led to a posture of awe that God would accomplish the mystery of salvation despite the human ignorance of the one who bore and birthed his Son.

Mary didn’t know.

Despite what the angel Gabriel revealed to her (Luke 1:26–38), she didn’t know everything her new baby was capable of. This doesn’t denigrate Mary, for she, like us, stood on the created side of the Creator-creature distinction. Hers was a human knowledge, a finite understanding.

But did Jesus know?

That is, did Jesus know all there was to know about who he was as God’s Son? And, if so, did Jesus know everything? After all, as the Nicene Creed says, he’s “very God of very God, begotten, not made, being of one substance with the Father.”

Not-So-Simple Question

On the one hand, the answer seems straightforward. One can even think of a snappy syllogism that makes it plain:

God is all-knowing.
Jesus is God.
Therefore, Jesus is all-knowing.

Passages also jump to mind where it’s clear that Jesus had knowledge reaching beyond human limitation: He knew that there was a coin in the mouth of a fish (Matt. 17:27), that the Samaritan woman had had five husbands (John 4:18), and that Lazarus had died before he and the disciples were alerted (John 11:14).

Mary didn’t know. But did Jesus?

On the other hand, the answer isn’t so straightforward: Jesus isn’t only God. He was also a baby boy who grew up to be a full-grown man. Luke 2:52 states that Jesus “increased in wisdom and in stature and in favor with God and man.” At the very least, this indicates that Jesus was bound by the normal course of human development in body and mind.

Does this really mean he didn’t know certain things? Growing up in a carpenter’s house, did he know how to fish? Growing up in first-century Israel, did he know what it was like to grow up in fifth-century Britannia? Growing up a boy, did he know what it was like to be a girl?

Startling Admission of Ignorance

Scripture, of course, doesn’t straightforwardly address these questions. But it does give one rather startling admission of ignorance in Matthew 24:36 and Mark 13:32. Concerning his second coming, Jesus says: “No one knows [the day or hour], not even the angels in heaven, nor the Son, but only the Father.”

There. We’re face-to-face with it. Jesus states his own lack of knowledge.

Jesus didn’t know.

This startling comment has been approached in different ways throughout church history. For example, the great fourth-century theologian Athanasius explained it like this: “[Jesus’s professed ignorance] is not the Word’s deficiency, but of that human nature whose property it is to be ignorant.” That seems simple enough: When Jesus talked about not knowing, it’s akin to his getting weary or hungry. That is, these are expressions of his humanity and his humanity alone. But then Athanasius complicates the picture. Commenting on John 17:1, where Jesus does seem to know that his hour has come, Athanasius basically argues that the incarnate Son of God can be knowing and unknowing at the same time. How can this be?

We need some Christological categories to help us at least understand—if not fully explain—such a comment by the incarnate Son of God.

Natures, Persons, and Classical Christology

This is where the language of the Council of Chalcedon (AD 451) can be helpful. When the second person of the Trinity became incarnate within the womb of the virgin Mary, he joined a human nature to his divine nature. It was an addition, not a subtraction. As Paul put it, Christ “emptied himself”—not by losing his divine nature, but by “taking the form of servant” (Phil. 2:7). Chalcedon called this the “hypostatic union”—a union of two complete natures “without confusion, without change, without division, without separation” in one person.

The council crafted such language in order to rule out heresies that had either subtracted from, confused, or divided the two natures. In contrast, the council emphasized the union of the natures within the singular person of the Son of God.

So how does this language help us with the question of Jesus’s confessed ignorance? Answer: by helping us see that when we face Jesus’s ignorance in Scripture, we’re not confronting a nature—we’re facing a person. A person who is different from every other person who has ever lived because he has two natures united within him.

If the Bible didn’t have the verses about Jesus’s ignorance in Matthew 24 and Mark 13, what would be lost?

Moreover, these natures don’t switch on and off by some toggle-switch deep within Jesus’s consciousness. The human nature doesn’t limit the divine (as God, the Son doesn’t lose his omniscience), nor does the divine morph the human (as man, his human mind doesn’t become omniscient—just as his body doesn’t become omnipresent). Rather, these natures with all their properties commune within the one person who then performs actions according to both natures.

But we must also remember: Natures don’t do things, people do. Better said, persons perform actions by virtue of their natures. This is true with Christ as with all other persons, but is complicated by the fact that he has two natures. It certainly appears that one nature is more reflected in certain actions than others. For example, sleeping in a boat reflects his human nature, and walking on water reflects his divine. Yet, while sleeping in a boat he upheld the world as the second person of the Trinity, and while walking on water he used real human feet. Still, all of these actions are attributed to the same person—the person of Christ. The Westminster Confession of Faith explains this biblical use of language in 8.7:

Christ, in the work of mediation, acts according to both natures, by each nature doing that which is proper to itself; yet, by reason of the unity of the person, that which is proper to one nature is sometimes in Scripture attributed to the person denominated by the other nature. (cf. Luke 1:43; John 3:13; Acts 20:28)

Pressing into the Mystery

If the Bible didn’t have the verses about Jesus’s ignorance in Matthew 24 and Mark 13, what would be lost? We’d certainly have a neat-and-tidy view of Jesus as omniscient. But neat-and-tidy tends to serve the interests of another kind of knowing—our own. Faith requires us to remember that, in the words of Hilary of Poitiers (AD 310–367), “What man cannot understand, God can be.” This should produce a posture of adoration, rather than one of grasping for exhaustive definition. As we approach the question of what Jesus did and didn’t know, it’s an opportunity to remember all that we cannot know but should still worshipfully affirm.

It’s also a reminder that our limitation of knowledge isn’t sinful. Jesus’s perfect humanity—even including his lack of knowledge—heals our humanity, so that we can rest in, rather than despise, the things we haven’t been given to know (Deut. 29:29). In not knowing when Jesus will return, we can patiently wait on God, trusting him only.

Jesus didn’t know . . . and Jesus knew.

I’ve made a case that when Jesus said he “didn’t know,” this was his person speaking according to his human nature. At the same time, according to his divine nature, he withheld this knowledge because in his infinite wisdom he knew it wasn’t the right time for his people to know (and this continues to be the case!).

So Jesus didn’t know . . . and he did.

Such are the paradoxes of the incarnation. But rather than repel us by their seeming absurdity, they should invite us to press into the mystery of Jesus Christ, Son of God and Son of Man.