Blake here uses the example of a chapel to muse on religion in general. He questions the existence of money and riches in the house of God, and reminds the Church of Jesus's attitude toward the rich. After all, Jesus routinely castigated the rich, providing regular verbal lashings of their coveting of material wealth and their indifference to their less-well-off brethren. In the opening stanza, the poor are left outside of the refuge, not even “daring” to enter. Blake argues that this is wrong.
There is a dual meaning to this short and simple poem. One theme to be taken away from “I saw a chapel all of gold” is the obvious comment on the falsity of religion that Blake is making. In this reading, it is the serpent that is the one strong enough to “break” in. The symbol of the serpent is not lost on any reader. Blake almost rhetorically awards the serpent for his rebellious victory over the chapel’s elite profligacy, despite his “slimy length” and “vomiting poison.”
The second meaning becomes almost as obvious as the first, once you know it is there. The poem is stuffed full of obvious sexual images. In this analysis, the “chapel of gold” is a representative for the temple of innocent love, the virgin body. This holy place is soon defiled by a repressed villain who can no longer bury his natural sexual drive. What begins with a beautiful image (line 1-2) is turned into a metaphor of violence and ugliness as the speaker revolts.
The images given to the reader become more obvious once he/she is aware of this undercurrent theme. The speaker “stands” outside the chapel weeping and worshipping until he can take it no longer. A “serpent rises[s]” between two “white pillars” eventually “forcing” its way inside. After his “slimy length” is set among “the rubies” he “vomits out poison” onto the sacred bread and wine. In the last two lines, the speaker is turned into a “sty” and “laid down among the swine” showing a remorse and regret for the heinous intrusion just surpassed.