The poem sets two scenes side by side. In the first, a preacher delivers a line about responsibility: those who have been given a lot owe a lot in return. In the second, the speaker takes a woman to a wine garden and the two of them enjoy themselves without restraint.
The humor comes from how the speaker seems to twist the sermon. "Given" can mean blessings or talents, and the speaker appears to treat the pleasure of the garden as one more gift to be used fully. Notice that "free" is repeated: he is free with her, and she is just as free with him. That gives the moment a sense of mutual, equal enjoyment rather than one person taking advantage of another.
The mood is relaxed, sly and a little cheeky. The title suggests the voice of a wine-loving, pleasure-seeking Persian-style poet, and the speaker's tone fits that. He neither apologizes nor argues. He simply sets the sacred and the sensual next to each other and lets the reader smile at the gap.