First, I would point out this enote page for a general discussion of the themes and symbolism of the story. To summarize:
- The story is about the struggle between good and evil, God and Satan, as represented by Delia and Sykes. Delia’s church membership, Syke’s use of the serpent to scare Delia, and Delia’s belief that “Sometime or ruther, Sykes, like everybody else, is gointer reap his sowing" suggest that the story is a symbolic working out of this conflict in the context of a rural, Southern black community.
- The story can also be read as a commentary on gender and power. Sykes’ power is based on his vanity: women have value determined by his sexual attraction to them. Delia’s “skinniness” is the excuse Sykes would use to run Delia out of her own home: he says to Bertha at one point, “Sho' you kin have dat lil' ole house soon's Ah kin git dat 'oman outa dere. Everything b'longs tuh me an' you sho' kin have it. Ah sho' 'bominates uh skinny 'oman. Lawdy, you sho' is got one portly shape on you! You kin git anything you wants. Dis is mah town an' you sho' kin have it." Delia’s power, on the other hand, comes from her hard work (the “sweat” of the title): this is how she is able to have the house, and support Sykes.
Another aspect of the story is race. Sykes’ distaste for Delia’s washing is due in part to it coming from the whites; Delia, for her part, looks to the whites as a kind of moral authority; at one point she says “Ah'm goin' tuh de white folks bout you, mah young man, de very nex' time you lay yo' han's on me,” a threat that seems to have an impact. There is a sense in which Delia’s work ethic aligns her with the values of white society, in opposition to the posturing of Sykes, but it is not clear that Delia’s working for the whites, while an “honest living,” can be considered a “good thing.”
The story problematizes both Sykes and Delia; Sykes is “bad,” no doubt, but Delia for her part does conquer her fear of snakes (and of Sykes) long enough to watch him die of snakebite. It is true that at the end she is liberated from him, but her own symbolic association with “goodness” and religious faith is called into question.