Seventeenth-century metaphysical poet John Donne often uses spiritual or religious images to describe erotic love. Let's look at how he does so in “The Canonization.”
The speaker begins by imploring someone (perhaps himself?) to be quiet and let him love. Criticize anything else about me, he says, but leave my love alone. Better yet, he continues, go focus on yourself. Earn some money, study, get a job, or look upon the king, the speaker pleads; just leave me alone to love.
Then begins an argument. Again, perhaps the speaker is arguing more with himself than anyone else, and he comes up with all kinds of reasons why he should be allowed to love his lady. First, it isn't hurting anyone, he claims. No ships have sunk. The weather hasn't changed. His love hasn't brought the plague down upon anyone. Life goes on as normal.
Apparently, though, the speaker is not satisfied with this argument. He needs something more, perhaps to respond to the counterargument that such a love might hurt him and his lover. No, he declares, their love makes them what they are, and if they burn and melt with love like candles, it is at their own cost. Yet they are made for this love, and in their love all kinds of mysteries find their solutions.
Even if he and his lover die from their love, the speaker proclaims, their legend will live on. Poets will write about them in sonnets or better yet, in hymns. Yes, the speaker now comes to his highest argument. People will write hymns about them, and they will be “canonized for Love” (line 36).
Here's where the spiritual/religious dimension enters the poem. The speaker and his lady are justified in their love because one day, when they are dead and gone, people will canonize them for their love. They will make them saints before the altar of love. The speaker envisions other eager lovers invoking them, calling on them for intercession, in their own trials of love. The speaker and his lady shared a “reverend love,” a love worthy of honor (line 37). They were “made one another's hermitage” (line 38), for they lived within the solitude of their love. Their love contracted the whole world into each other's eyes. They were the whole world to each other; when one looked at the other they saw the whole world. Now, the speaker says, other lovers will ask them to “beg from above” (line 44) that they may share the same kind of love. This is the highest possible argument the speaker can think of to justify his love. One day, he and his lady will be like saints, canonized for their love and interceding for other lovers.