The Advent Christian Church, also known as the Advent Christian General Conference (ACGC), is a "first-day" body of Adventist Christians founded on the teachings of William Miller in 1860. The organization's Executive Director is Reverend Steve Lawson, and its President is Reverend John Gallagher.

Adventism is a branch of Protestant Christianity that believes in the imminent Second Coming of Jesus Christ. It originated in the 1830s in the United States during the Second Great Awakening when Baptist preacher William Miller first publicly shared his belief that the Second Coming would occur at some point between 1843 and 1844. His followers became known as Millerites. After Miller's prophecies failed, the Millerite movement split up and was continued by a number of groups that held different doctrines from one another. These groups, stemming from a common Millerite ancestor, collectively became known as the Adventist movement.