About Seventh-day Adventists ®. The Seventh-day Adventist Church is a mainstream Protestant church with approximately 19 million members worldwide, including more than one million members in North America. In the Seventh-day Adventist church, they call Oct. 22, 1844, the "Great Disappointment." It was the day the world didn’t end. 3,500 disappointed believers regrouped to form the Seventh-day Adventi. Warwick Seventh-day Adventist Church: Join us for our six-day seminar. Tune to…