Few poems begin with a command as shocking as "Spit in my face you Jews, and pierce my side." The speaker casts himself as a bystander at the Crucifixion who demands to be treated as Christ was: buffeted, scoffed at, scourged, crucified. The first line is also a trap. Within a few lines the poem has turned the accusation around. The speaker is not really blaming anyone else. He is saying that his own sins are worse than those of the people who killed Christ. The poem draws on a long Christian tradition of blaming Jews for the Crucifixion, and modern readers may find that uncomfortable. But the poem's own movement is to pull that blame onto the speaker, who claims the greater guilt.
The argument is tightly built. "I have sinned, and sinned," he says, and the doubled verb makes the sin feel habitual, a grinding repetition. Only Christ, "Who could do no iniquity," has died. Then comes the logic that drives the octave: even the speaker's own death could not "satisfy" his sins, because they "pass the Jews' impiety." The reason arrives in lines 7 and 8: "They killed once an inglorious man, but I / Crucify him daily, being now glorified." The enjambment leaves the word "I" stranded at the end of the line, and the speaker stands exposed for a moment before the verb lands. The contrast between "once" and "daily" and between "inglorious" and "glorified" makes the speaker's sin sound ongoing, and worse because it is committed against someone now exalted.
The rhyme scheme is the Petrarchan one, with an octave rhyming ABBAABBA and a sestet that settles into CDCDEE. Look at the B-rhymes of the octave: "me," "he," "impiety," "I." Three of the four are pronouns, so sinner and Saviour are bound together in rhyme (me/he) even as the argument insists on how far apart they are. The rhythm helps with the shock. "Spit" takes the stress that would normally fall later in an iambic line, so the poem opens with a blow. The verbs that follow pile up like a beating, and the hard, hissing sounds of "scoff, scourge" give them extra bite.
At line 9 the mood changes. "Oh let me, then, his strange love still admire" drops the violent imperatives for something closer to wonder. "Strange" here suggests not only unusual but almost foreign, a kind of love the speaker cannot fully understand. The poem's logic has quietly reversed. The speaker began by demanding punishment, but his own punishment would be inadequate, and Christ has already "bore our punishment." The comparison with kings makes the point: "Kings pardon," which means a ruler simply cancels the penalty, "but he bore" it himself.
The second comparison is the cleverest. Jacob, in the Old Testament story, put on rough clothing, "vile harsh attire," to pass himself off as his brother and gain a blessing. Donne's word "supplant" captures the trick, and "gainful intent" makes the motive plain. Against this stands God, who "clothed himself in vile man's flesh." The same word, "vile," is used for both costumes, but the purposes are opposites. Jacob dressed up to get something. God put on humanity to give something up.
The closing couplet carries the paradox that holds the whole poem together: God took on flesh "that so / He might be weak enough to suffer woe." The line is almost entirely made of short, plain words, and the long "o" of "so" and "woe" slows it to a sorrowful close. The phrase "weak enough" is the surprise. Weakness is treated as something God had to achieve, because an all-powerful being could not suffer unless he chose to become vulnerable.
The poem matters because it joins raw emotion to rigorous argument. Instead of simply lamenting his sinfulness, the speaker reasons his way, step by step, from self-condemnation to awe. The movement from violent self-accusation to a quiet, almost astonished conclusion gives the sonnet its drama, and it makes the reader feel that faith here is something argued over, not just accepted.