I must admit, we evangelicals have developed an allergy to things eternal, especially when it comes to our doctrine of the Trinity. To be brutally honest, we are prone to conflation. We approach the Bible assuming history is its only focus. Ironically, this approach is a failure to be biblical enough. Yes, Scripture’s story line does take narrative form, focused as it is on salvation history. But the biblical authors never stop there, nor is narrative an end in and of itself. Never do they shove the infinite, incomprehensible Trinity into our tiny box of history, limiting who God is to what God does, prioritizing function over being. Either in their presuppositions (consider the Psalms) or in their theological conclusions (purview Paul’s letters), they intend the reader to read theologically. More to the point, the biblical authors are not so focused on the historical facts of the life of Christ that they are unconcerned with his eternal, trinitarian origin prior to the incarnation. They are not so earthly minded that they are of no heavenly good.

We should not be either.

Consider the opening of John’s Gospel, for example. As I share in Simply Trinity: The Unmanipulated Father, Son, and Spirit(Baker), I often hear pastors advising churchgoers to give the Gospel of John to someone they are trying to evangelize. That’s for good reason, too: John’s Gospel lays out the gospel with lucid conviction, bringing the unbeliever face-to-face with the crucified and risen Christ and the many gifts he gives to all recipients of his grace. That’s why we love texts like John 3:16; we desire to tell the world about God’s Son so that they might receive eternal life.

But in our rush to talk about eternal life, we sometimes skip to the second half of John 3:16 and forget to talk about the eternal Son. As the first half of John 3:16 says, God “gave his only begotten Son” (KJV). Let those words marinate: God . . . gave . . . his . . . only begotten . . . Son. When we rush to the benefits the Son brings and skip over the identity the Son has in eternity, we neglect not only the first half of John 3:16 but the first two chapters of John’s Gospel—chapters, need I remind you, that precede John 3.

Did you know, for instance, that John begins his Gospel not with the eternal life we receive but with the life the triune God enjoyed in eternity? Go back to the opening of John 1 and what do you read? “In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God” (1:1–2). Before we get to the good news about Jesus and the eternal life he brings, let’s take a step back and consider, as John does, where this Jesus originates from in the first place. This will be hard, but let’s put off what God has done in creation and focus first on who God is apart from creation. Why would we do that? Here’s why: unless you understand who God is apart from you, you will never understand the importance of what God has done for you, at least not in full. I realize how counterintuitive that sounds, holding off on the history of redemption—your history—to talk about things eternal. Abstract and esoteric perhaps. But John is convinced that in doing so you will have a better grasp of who this Word is and why he became flesh and dwelt among us. Furthermore, a long line of church fathers also believe that John’s approach avoids a dirty swamp of heresies, many of which threaten to conflate who God is in and of himself (ad intra) with how God’s acts externally (ad extra) toward his creation.

Notice what John does first: he begins in the beginning. But what John means by the beginning is probably not what you think. He echoes the language of creation from Genesis to talk about the eternal God who made creation, and who this God must be before any rose bush or palm tree came into existence. As the church father Basil of Caesarea once pointed out, before all ages, there was God and nothing else. Before the cosmos existed, there was God and him alone. Except alone may sound as if he was lonely. He was not. For in the beginning, says John, was the Word—John’s way of referring to the Son. Coeternal, this Word was with God. Coequal, this Word was God. It’s hard to more closely identify the Word with God than this. He is coequal with God as the one who was God himself.

John’s choice of language—Word—is strategic. For soon enough he will tell his reader that this Word is none other than the Son of God himself. A word is worded by its speaker, meaning there is a source. Likewise with the Word: as the Word of God, he comes from God from all eternity to reveal God to those in history. John will spell this out in more detail when he switches his imagery from Word to Son (1:14). As Son, he is from his Father, for that is what it means to be a son after all. Yet since this is God we are talking about, the Son is generated from the Father’s nature before all ages. Never was there a time when the Father was without his Word, because never was there a time when the Father did not beget his Word. Otherwise, in no way could John say the Word (the Son) was both with God and was God. In John’s mind the Word (the Son) is both distinct from God the Father (the Word was with God) and one with God himself (the Word was God). But distinction (in personhood) and identity (in essence) is only possible because of eternal generation: the Son is distinct precisely because he is begotten by the Father; the Son is coequal precisely because he is begotten from the Father’s nature, the same divine nature the Son shares.

Having established the Word’s eternal relation of origin in verses 1–2, John is now ready to introduce the world. It is because the Word is eternal (never was there a time when the Word was not with God) and it is because the Word’s origin is divine (never was there a time when the Word was not God) that “all things were made through him, and without him was not any thing made that was made” (1:3). Through the Word, God created the cosmos ex nihilo. To clarify, it’s not the Word who is created out of nothing; the world is created out of nothing by the Word.The Word is not created along with creation, nor is the Word created prior to the rest of creation. Rather, the creation is brought into existence through the Word whose existence never began, whose divinity never had a starting point.

But it’s not just creation that is attributed to the Word; salvation is as well. No work of God is kept from the Son. Transitioning metaphors, John calls the Word the “life” and the “light” (1:4–5), the “true light” that gives life to the world (1:9). He can do that since the “world was made through him” (1:10). But here’s something more remarkable still: in order to give life to the world, the Word became incarnate. “And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth” (1:14 KJV).

Extraordinary! The eternal Word, the Son of God himself, the one who is begotten from the Father from all eternity, was sent by the Father to ensure we would be recipients of his grace. On the one hand, says John, “No man hath seen God at any time” (1:18), an observation the Old Testament itself reiterates (Deut. 4:15). On the other hand, “the only begotten Son, which is in the bosom of the Father, he hath declared him” (1:18 KJV). How appropriate, then, for John to call the eternal Son the eternal Word. It is because he is the only begotten Son from the Father, begotten before all ages as the Word who was with God and was God, that he can then, at the proper time, become incarnate and reveal the Father to us for our salvation. He is the revelation of God in the flesh.

From John 1 forward, John and Jesus will both move back and forth from eternity to history, from God in himself to God toward us, always demonstrating that the latter is contingent on the former. But never, never conflating the two. As Jesus claims repeatedly to be the way to salvation in John’s Gospel, he will also back up his right to make that claim, especially when the religious leaders question his authority, by appealing to his eternal origin from the Father. It is only because he is begotten by the Father from all eternity that he can then claim to be sent by the Father to become incarnate in history. His eternal relation to the Father constitutes his redemptive mission to the world, but not vice versa.

Get that order right, and we see the gospel in proper trinitarian perspective; get that order wrong, and we misuse the gospel to redefine the Trinity in eternity.

Matthew Barrett is the author of Simply Trinity: The Unmanipulated Father, Son, and Holy Spirit (Baker). He is the host of the Credo podcast and associate professor of Christian theology at Midwestern Baptist Theological Seminary. Follow him @mattmbarrett.