Open Matthew 3:13-16.
Why did Jesus need to be baptized? Others came confessing their sins (3:6). Jesus joined them. John refused, at least initially. Why did Jesus think he should be baptized to fulfil all righteousness (3:15)?
Our difficulty is that we think individually rather than corporately. Matthew told us Jesus would save his people from their sins (1:21). We mishear if we think he meant he forgives each individual for their personal failures.
By his people, Matthew meant the Abrahamic family. By their sins, he meant their corporate disobedience, the reason their heavenly ruler had handed them over to the nations. That’s why Israel was stuck in her sins.
So imagine their joy when John announced the end of the captivity and the restoration of God’s kingdom. “God’s reign is at hand. Get ready!” People responded by confessing their sins (3:6). It’s not primarily about individuals acknowledging personal failures. It’s Israel, after 600 years of foreign rule, asking God to forgive and restore his nation.
If you’re still struggling to get past our framework of individual sin, read Daniel 9:3-19 carefully. Daniel isn’t confessing his own personal guilt. He confesses their corporate guilt, that God was right to treat them as he has:
Daniel 9 (ESV)
4 I prayed to the Lord my God and made confession, saying, “… 11 All Israel has transgressed … 13 As it is written in the Law of Moses, all this calamity has come upon us; yet we have not entreated the favour of the Lord our God, turning from our iniquities and gaining insight by your truth. … 15 And now, O Lord our God, who brought your people out of the land of Egypt with a mighty hand, and have made a name for yourself, as at this day, we have sinned, we have done wickedly. 16 Let your anger and your wrath turn away from your city Jerusalem, your holy hill, because for our sins, and for the iniquities of our fathers, Jerusalem and your people have become a byword among all who are around us.
Then John comes, announcing Jesus as the one who will purify Israel. John says the Messiah will chop down the unproductive branches, and burn the chaff. But what actually happens confuses John. Jesus climbs into the water.
Jesus will purify his people, but he’ll do that by identifying with them. Their king will be one of them. They have been unable to fulfil all righteousness, so Jesus enters the water to do it for them: to fulfil all righteousness (all the requirements of their heavenly sovereign’s law) for his people.
In the Old Testament, the relationship between God and his people was mediated by priests. As we saw, they were set apart for this task with a ceremony that included washing them (Leviticus 8:6). Jesus’ baptism is that kind of commissioning. He entered the water with and on behalf of his people. He was washed as a symbolic commissioning for his priestly ministry. When he purifies his people, all the righteous requirements of the heavenly sovereign are finally fulfilled.
That’s the thought-train that runs through Isaiah 40–55. God called Israel to be his servant to the nations, but Israel was an unfaithful servant. There was no one to complete her mission, so God announced that he would step in to fulfil her calling. Matthew alludes to the servant songs of Isaiah several times. He understands Jesus as the one who enters the waters with his failed people, shoulders their grief and iniquity, offers himself to resolve their guilt, and raises them back to life in his resurrection (compare Isaiah 53:10). Jesus (God’s servant) identifies with Israel (God’s servant) as their priest.
Think corporately. Jesus was baptized not for his own personal guilt, but for the guilt of his people. He had to become their priest and act on their behalf if they were ever to fulfil all righteousness.
What others are saying
Craig S. Keener, The Gospel of Matthew: A Socio-Rhetorical Commentary (Grand Rapids, MI: Eerdmans, 2009), 132:
Since “fulfilling righteousness” elsewhere in Matthew may pertain to obeying the principles of the law (1:19; 5:17, 20; cf., e.g., Sib. Or. 3.246) as well as to the mission of Jesus and his followers (5:10; 11:19; 27:19), Jesus probably here expresses his obedience to God’s plan revealed in the Scriptures. Matthew’s readers familiar with the Scriptures would already understand that Jesus sometimes “fulfilled” the prophetic Scriptures by identifying with Israel’s history and completing Israel’s mission (2:15, 18). This baptism hence represents Jesus’ ultimate identification with Israel at the climactic stage in her history: confessing her sins to prepare for the kingdom (3:2, 6). Jesus’ baptism, like his impending death (cf. Mk 10:38–39 with Mk 14:23–24, 36), would be vicarious, embraced on behalf of others with whom the Father had called him to identify.
Leon Morris, The Gospel according to Matthew, The Pillar New Testament Commentary (Grand Rapids, MI: Eerdmans, 1992), 65:
Jesus might well have been up there in front standing with John and calling on sinners to repent. Instead he was down there with the sinners, affirming his solidarity with them, making himself one with them in the process of the salvation that he would in due course accomplish. If there is a reference to Isaiah 53, it is relevant to note that in that chapter we read: he “was numbered with the transgressors” (Isa. 53:12). … In submitting to John’s baptism Jesus is pointing to the people’s need. Matthew pictures Jesus as dedicating himself to the task of making sinners righteous, an appropriate beginning of his public ministry.
Tom Wright, Matthew for Everyone, Part 1: Chapters 1-15 (London: SPCK, 2004), 21:
We are on our feet, expecting a great leader, perhaps the living God himself, sweeping into the hall with a great explosion, a blaze of light and colour, transforming everything in a single blow.
And instead we get Jesus. The Jesus we have only met so far, in Matthew’s gospel, as a baby with a price on his head. A Jesus who comes and stands humbly before John, asking for baptism, sharing the penitential mood of the rest of Judaea, Jerusalem and Galilee. A Jesus who seems to be identifying himself, not with a God who sweeps all before him in judgment, but with the people who are themselves facing that judgment and needing to repent.