Perhaps the greatest public controversy of his early career arose from his studies of Seventh-day Adventist theology. From its earliest days until the 1950s, the Seventh-day Adventist Church was regarded by Evangelical Christians and mainstream Protestants as either an extreme sect or heretical cult. Martin had initially accepted the prevailing Protestant opinion about the heretical status of the Seventh-day Adventists. He indicated his opposition to Adventist teachings in a brief paragraph in the inaugural edition of his book "The Rise of the Cults," published in 1955.