Millions are in mourning following the death of spiritual leader Sun Myung Moon, who passed on Monday at 92. As the founder of the Unification Church in 1954, Moon established a global following of millions — known as ‘Moonies’ — and a business empire, both of which now face an uncertain future.

A statement from Unification Church US, one of the largest chapters, played down fears by saying that the leader’s wife — “True Mother” Hak Ja Han Moon — would protect her husband’s religious vision. His youngest son, Reverend Hyung Jin Moon, had already been appointed international president of the church.

The church’s UK leader Pastor Simon Cooper said this was a moment of opportunity. “We could now see more development from the grass-roots. Local congregations will have a stronger position with less direction from the world mission.”

Although best known for eye-catching religious displays, such as mass marriages of thousands at a time, Reverend Moon also established a lucrative business empire, including newspapers and arms manufacturers. Leadership has been problematic, with power changing hands between Moon’s sons, before Hyung Jin Moon took charge.

“As tremendous wealth is available to anyone who takes over — we shouldn’t be surprised if the passing of a leader provokes a power struggle,” Cult Information director Ian Hawarth, who has studied the group for over 30 years, told Metro. The church’s popularity is also under threat, according to Hawarth. “Some would suggest a global decline over the last decade … although there has been a build-up of influence in South America.”

The church is officially in mourning until Moon’s funeral in 15 days, after which it must begin a new era without its founding father.