In Reformed and Reformed Baptist theology, Jesus’ baptism is not viewed as a “repentance baptism” for personal sin (since Christ is sinless), but as a purposeful, redemptive-historical act that publicly inaugurates and signals what kind of Messiah he is: the obedient Servant who identifies with his people, receives the Spirit without measure, and begins his mediatorial work.

Below is a synthesized summary (with representative emphases you’ll see across historical and contemporary Reformed/Reformed Baptist sources).

1) “To fulfill all righteousness” = covenant obedience as the Second Adam

When Jesus tells John, “thus it is fitting for us to fulfill all righteousness” (Matt. 3:15), Reformed writers commonly take this to mean: Christ is intentionally taking his place under God’s covenantal demands as the representative man. This is part of his active obedience—his lifelong law-keeping and submission to every ordinance appointed by the Father for his public work.

• Calvin (classic Reformed) stresses that Christ’s baptism is fitting not because Christ needs cleansing, but because Christ willingly receives what God appointed, thereby confirming his obedience and advancing the Father’s saving plan.
• Reformed Baptist framing often adds: baptism here is not “proof Jesus had sins,” but a sign-act of messianic obedience, the beginning of his public mission as the righteous covenant head.

2) Identification with sinners (solidarity) without being a sinner

John’s baptism is “for repentance” (Mark 1:4). Jesus does not come as a penitent; he comes as the one who will bear penitents’ guilt. Reformed theology commonly describes this as solidarity: the sinless one steps into the place where sinners stand.

This anticipates the larger pattern of substitution:

• At the Jordan, Christ stands with sinners.
• At the cross, Christ stands for sinners (bearing sin and curse).
• In resurrection/ascension, Christ stands ahead of sinners as the firstfruits and forerunner.

3) A public inauguration and commissioning of his messianic ministry

Jesus’ baptism functions like an installation moment. Immediately after, the heavens open, the Spirit descends, and the Father speaks (Matt. 3:16–17). Reformed interpreters typically see this as the formal launch of Christ’s public ministry.

This inauguration includes:

• Public attestation: The Father’s voice identifies Jesus as Son/Servant (“my beloved Son… with whom I am well pleased”).
• Public authorization: John’s role as prophetic forerunner is confirmed; Jesus is “the one” John has been preparing for.
• A decisive transition: from private life to public, kingdom-proclaiming ministry (preaching, miracles, gathering disciples).

4) An anointing with the Spirit (Messiah = the Anointed One)

The descent of the Spirit is read in Reformed tradition as Christ’s messianic anointing for his mediatorial office—especially highlighting Isaiah’s Servant imagery (“The Spirit of the Lord is upon me…”).