SYDNEY, Australia — At a regular Sunday morning service, before the praise songs and a sermon on resilience, a pastor at one of Sydney’s largest Pentecostal churches mentioned a congregant who was usually among those worshiping there.

Church had always been a part of his life and for the past decade, his spiritual home has been this bustling sanctuary with a cross formed from bright lights.

But he was not with them this past Sunday. On Friday, he became Australia’s newest prime minister.

“I’m incredibly hopeful — hopeful for the future of our generation,” said Alison Bonhomme, a senior pastor at Horizon Church, reflecting on the political tumult that led Scott Morrison to become the country’s leader.

A burst of applause followed.

Mr. Morrison and his faith represent a break with tradition in Australia, where politics has long been ardently secular. He is the first prime minister to come from one of the country’s growing evangelical Christian movements, leading many experts and voters to wonder how his Christianity might affect various issues, from foreign policy to social policy.