About 20 people are to be baptized by the Bishop of Sodor and Man in a special "baptism on the beach" ceremony taking place at Peel Bay.
Thousands of people are expected to line the promenade on Easter Sunday to watch the island's first interdominational baptism.
The Right Reverend Robert Paterson said the service would not be "traditional".
The event begins at 1530 BST. If the weather is bad, it will be moved to the grounds of St German's Cathedral.
Anglicans, Pentecostalists and Roman Catholics will be able to reaffirm their faith, in or out of the water, he said.
"We're going to have a short and fairly lively service, not the conventional thing you'd expect if you went to a church, particularly as we won't be having an organ on the beach," he added.