Abigail was always smugly adamant that she could spot evil-doers, witches and the devil possessed, but when confronted by Barnabas, she refused to believe. No doubt she was a repressed, vinegary spinster and perhaps her zealotry wasn't just an outlet for her repression, but a mantle to cloak decades of bitter disappointment. Maybe facing something truly unnatural and evil tore that mantle off (made all the more shocking as it was her own kin) and her final moments involved some major reassessment of her beliefs. Probably not, though. I wasn't sorry to see her go, she was an annoying quidnunc.
I've always liked the scene with Trask and Daniel. When Daniel told Trask that he was the one who looked like the devil, Trask's smile conveyed a lot, at least to me. I don't know if it was scripted, direction, or accident, but Trask seemed genuinely amused and able to laugh at himself. During most of the conversation with Daniel, Trask came across as a more traditional minister, patiently and quietly attempting to teach a child about good and evil. Of course, that didn't last long and he was right back to the usual foaming-at-the-mouth fanaticism. I loved Naomi comforting Daniel and taking Trask to task.