**Summary**: This paper explores the history, core doctrines, and biblical interpretations of the Seventh-day Adventist (SDA) Church, beginning with its origins in the Great Disappointment of 1844. Key doctrines examined include the observance of the Sabbath on Saturday, the imminent Second Coming of Christ, the unique investigative judgment starting in 1844, health and lifestyle practices, the sanctuary doctrine, and the role of Ellen G. White as a modern prophet. A critical analysis compares SDA beliefs with mainstream Christian orthodoxy, highlighting areas of doctrinal divergence and theological debate. #GreatDisappointment, #SeventhDayAdventist, #SDA, #Sabbath, #SecondComing, #InvestigativeJudgment, #EllenGWhite, #HealthAndLifestyle #SanctuaryDoctrine, #SpiritOfProphecy, #BiblicalAnalysis, #ChristianOrthodoxy, #ProtestantChristianity, #Eschatology, #DietaryLaws, #SabbathObservance #brendonnaicker #theologyschool #swindonchurch