"You're living on holy ground," a man said to William Wyatt after knocking on the front door of his house on River Road. That was news to Mr. Wyatt, who had purchased the house in 1986. The man, whom Mr. Wyatt describes as "an old testament figure," explained that "the third incarnation of Jesus Christ had lived in this house." As he left, he said he was taking legal steps to get the property back but that Mr. Wyatt and his wife Sally shouldn't worry. The man never returned but the story made Mr. Wyatt aware that his five-room house had more history than he imagined. The "holy ground" turned out to include not only Mr. Wyatt's house, but also Great Island and an adjacent parcel of 35 acres on the West Branch of the Westport River once owned by the Mission of the Holy Spirit. The mission was the subject of Mr. Wyatt's talk at the Westport Historical Society at the Bell School House on August 12. (Mr. Wyatt is president of the Westport Historical Society.) Using information from the archives of Fall River newspapers, the Mission of the Holy Spirit's web site, and local knowledge, Mr. Wyatt described a little-known sect that established itself on Great Island in Westport in 1921. The mission existed rather quietly until a sensational trial in 1925 spelled its demise here. Mr. Wyatt said, "The tale I shall tell will speak of religious convictions, belief in a savior figure, utopianism, chicanery, and delusion all tangled together inextricably."