Answer:
Sermon.
Step-by-step explanation:
Discourse is the act of communication where words and actions are used. It signifies the very act of being in discussion/ debate with others about any topic or issue.
Considering the given passage, the most likely meaning of the word "discourse" can be sermon. This is because the speaker s talking about Tom who attended a church congregation. And in this process, he was referring to the very act of being in communication/ active participation with the rest of the congregating members. So, when the speaker states "he seldom knew anything else about the discourse", he means that Tom hardly knew anything else about the sermon.