ROME — Pope Benedict XVI’s surprise announcement Monday that he will resign set off a flurry of speculation about his replacement, who will be called upon to guide the Roman Catholic Church through an increasingly secular era in which the church has lost the certainty it claimed for centuries.

Some Vatican observers predicted that the growing importance of the developing world to the church could weigh on the decision and, perhaps, lead to the choice of a non-European pope. But the voting bloc of cardinals coming from Europe remains sizable and influential, analysts said.