Watts opens with a job description. "'Twas the commission of our Lord," the first line announces, and the order that follows, "Go teach the nations, and baptize," comes straight from the Gospel verse printed above the hymn. A hymn about baptism might be expected to begin with water or with feeling. This one begins with authority, like an official document being read aloud. That sets the tone for the whole piece, which is less a private meditation than a clear explanation of why a church baptizes and what the act means.
The first two stanzas trace a journey. The command is given, the "nations have received the word," and Christ, enthroned "upon th' eternal hills" with "grace and pardon in his hands," sends his covenant outward "to bless the distant British lands." The picture is of a king with full hands and a charter travelling with its wax "seals" attached. "Seals" is the key word, and it returns in the last stanza when the singers "seal our cov'nant with the Lord." The phrase "distant British lands" is also quietly striking. Judging by it, the imagined singers are British, and they are placed at the far end of a long delivery route, the people the message has finally reached.
The third stanza is the hinge, and its argument fits into one line: "our sense assists our faith." Faith is invisible, but water can be seen and felt, so the ritual works like a picture in a textbook that "shows us what his gospel means." The reference printed above the hymn points to Acts, yet the poem gives the call to "Repent, and be baptized" to Christ himself ("he saith"). The commission and the call to repentance end up in a single divine voice.
The fourth stanza holds the most vivid imagery, in two similes. "Our souls he washes in his blood, / As water makes the body clean" asks us to accept a paradox, since blood normally stains and here it cleans. The everyday comparison with washing makes the strange claim easier to take in. Then the Spirit "Descends like purifying rain." The verb shifts the picture from scrubbing to something falling from above, which suggests that grace here is a gift received rather than a task done.
The sound of the poem follows the same path. It is written in long metre, quatrains of eight-syllable lines with a steady iambic beat, which a congregation can sing and remember easily. The rhyme scheme is ABAB throughout, but the quality of the rhymes changes. The first and last stanzas rhyme cleanly (Lord/word, baptize/skies; thee/Three, Lord/record). In the middle the rhymes loosen into half-rhymes: sins/means, blood/God, clean/rain. Whether or not Watts intended it, the chiming relaxes just where the ideas are most abstract and the imagery most strained.
The final stanza changes the grammar. For four stanzas everything is "he" and "his": he sits, sends, saith, washes. Now the singers speak to God directly: "we engage ourselves to thee." "Engage" carries its older sense of pledging, and the legal language gathers into a final prayer that "the great eternal Three / In heav'n our solemn vows record!" God becomes the witness who enters the promise in a register. The "Three" also recalls the Father, Son and Spirit named in the verse from Matthew that opens the poem, and the hymn has by now touched each in turn through "our God," "our Lord," and the "good Spirit."
What makes the hymn worth reading is how it explains a ritual in the language of everyday life. Baptism becomes a sign, a seal, a signature and a shower of rain, so an abstract doctrine turns into things a singer can picture. The poem begins with God's action and ends with a human promise, and the shift from "he" to "we" reproduces the structure of the covenant it describes: an offer is made, then answered. The writing is plain and sometimes plodding, but that plainness is the point. It is verse built to teach, and to be sung by many voices at once.