Patrick Coppeard, 43, convinced members of his congregation to give him money to invest. He conned 61 people out of £5.4 million before losing £3.4 million of it, primarily through gambling.
Mr Coppeard was a former managing director of Merrill Lynch, the wealth management division of the Bank of America. He also used to be a magistrate.
David Jaques said Patrick Coppeard scammed him out of more than £280,000 two days after he had sold his house.
According to The Daily Telegraph, Mr Jaques claims Mr Coppeard telephoned him and said: "God has told me to give you a ring when looking for investment."
The churchgoer also said: "I'd known him for 20 years from church. I knew he was a financial man and a magistrate, so I trusted him."
Coppeard eventually handed himself in to police, and admitted running the investment scheme at a hearing.
Passing sentence, Judge Anthony Goldstaub said: "You constructed a web of financial deceit in which you trapped a mass of trusting and vulnerable people.
"These people believed in you and you brought them to financial ruin."
The court was told that Coppeard's victims are likely to get back just £1 from every £10 they gave him.
A spokesman for St John's Church, where Mr Coppeard was a trustee, said the congregation was "distressed" to see a fellow Christian in such a "predicament".