The speaker treats Sunday, the traditional day of rest and worship, as a gift of free time, and decides to spend it on love and sin rather than prayer. The title, "Sabbath," sets up the expectation of holiness, and the poem quietly turns that expectation upside down.
What stands out is the word "ceremony." The speaker doesn't just indulge in sin; they make a ritual of it, giving pleasure the same care and seriousness that religion gives to worship. The last image, reading the Book of Martyrs in bed, is a wry, intimate comparison. It suggests that sin can be as absorbing as a gripping, solemn book, and perhaps that the speaker finds something both guilty and delicious in mixing the sacred with the sensual.
The mood is relaxed, playful, and a little mischievous. The short lines and plain language make it feel like a private, lazy confession, spoken without much shame.