You'd think that in a poem about a funeral, the dead person would do the haunting. But in "I felt a Funeral, in my Brain," religion – specifically New England Protestantism – does the haunting. Not literally, of course. But the religious service in this poem is anything but a source of peace and comfort. Religion keeps invading on her space. Although church is supposed to bring a sense of community into one's life, the speaker of this poem feels isolated and abandoned.
"I felt a Funeral, in my Brain" is not about traditional religion. Dickinson treats the funeral as a secular ritual.