Peter Ernest Bourne from Great Stukeley near Huntington is also being placed on the sex offender's register for the rest of his life after being found guilty of 14 offences, including rape.
Detective Constable Andrew Roe from Sussex Police said: "Due to the abuse that he subjected these individuals to, it has taken great bravery and strength for these individuals to come forward.
"Our thanks go to all of Bourne's family still in Sussex who supported the prosecution case with information, and especially to the three victims, now adults in their fifties, came to court to give evidence against them."
The 79-year-old of Moorefield Way was convicted of one count of rape, five counts of indecency with a child and eight indecent assaults - following an eight-day trial at Brighton Crown Court.
He has served as a lay preacher at a number of evangelical and Baptist churches.
DC Roe also said: "Bourne had taken advantage of their vulnerability and exploited them each separately, for his own sexual gratification over several years.
"He refused to admit his guilt throughout, and when arrested he made no comment to all questions put to him."
Bourne targeted the youngsters in the Southwick, Hove (pictured) and Worthing areas of East and West Sussex during the 1960s and 70s - when they were aged between nine and 16.
An investigation into the pensioner was prompted two years ago when officers were first alerted to concerns about Bourne.
DC Roe added: "We also discovered that Bourne, who worked in a range of roles, including as a charity worker, a coal man and a driver, was also a lay preacher in various churches including evangelical and Baptist churches, in Sussex and elsewhere."
Officers confirmed that Bourne got to know his victims through his personal life and not through his church activities.
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