The opening paragraph of the chapter provides a great place to begin to analyze mood:
A throng of bearded men, in sad-colored garments, and gray, steeple-crowned hats [...] was assembled in front of a wooden edifice, the door of which was heavily timbered with oak, and studded with iron spikes.
Words like "sad-colored" and even "gray" point to a bleak and cheerless mood. Further, the fact that the hats are "steeple-crowned" clues us in on how prominent a role religion will play in this text, but, combined with the other words in the paragraph, we don't get the sense that we are talking about religion in some kind of uplifting, inspirational sort of way; no, this religion seems dark and punitive. Next, the building is described in terms of the heaviness of its wood and the punishing description of the iron spikes. That the materials are so unyielding -- oak and iron -- has implications for the people just described and the community that built this edifice. This description reveals the mood to feel harsh, strict, and tightly controlled. Finally, the "iron spikes" contribute to a menacing mood; there is danger here, and the danger comes at the hands of the community that would build and then congregate around such a building.