Customers at Ahn’s café church can peruse a selection of Christian literature while nursing their lattes, which are about a dollar cheaper than at some of the neighborhood’s big-name franchises. A cross-adorned wooden shed in the corner, marked “Prayer Room,” contains a desk with a Bible on top. The sanctuary is located in a windowless room in the back, behind the espresso machine and industrial-strength coffee grinder.

Ahn told me he welcomes newcomers who, like him, feel Christianity in South Korea has become “too institutionalized.” That seems to be a sentiment shared by many worshipers in their 20s and 30s, who are, according to reports, increasingly leaving their churches amid feelings of disillusionment with organized religion.

And many don’t hold the same political views as older generations.

“Christians over the age of 50 are more likely to vote for the conservatives,” said Ms. Lee, a 40-year-old mother of three who was slowly finishing an iced vanilla latte at Jesus Coffee after the service. “We think differently from them.”

This generational divide mirrors a rift among the general population: According to a recent Gallup poll, ahead of Tuesday’s election most South Koreans aged 60 or older preferred the conservative or centrist politicians who take a hardline policy on North Korea, while voters in their 30s overwhelmingly favored the progressive candidate and care more about clamping down on corruption. Indeed, in a survey conducted by local pollster RealMeter, 27.5 percent of respondents said that a candidate’s “intention to resolve deeply-rooted corruption” was the most crucial quality; by contrast, only 18.5 percent said “protection of national security and liberal democracy” was most important.

Unlike American evangelicals, who have long been considered a coherent voting bloc, Korean “evangelical voters are not a unified bloc, and the voting patterns are complex, but politicians pay attention because many voters are evangelical,” David Halloran Lumsdaine wrote in Evangelical Christianity and Democracy in Asia. Survey data about the impact of religion on voting in previous elections is scarce, but interview data suggest that “Christians’ voting responds more to regional than religious affiliations,” Lumsdaine wrote.

Still, South Korean Protestants have long been reliable supporters of the country’s right wing due to a shared political ideology. The prosperity gospel and staunch opposition to communism are staples for many of Korea’s evangelical preachers, which align them with the agenda of pro-business and anti-North Korea politicians.

For the generation of Koreans who remember a time of war and poverty, these messages still resonate, but for those who have come of age in an era of relative peace and wealth, the prosperity gospel “doesn’t have the same magic appeal,” according to Brother Anthony, a longtime observer of South Korea’s religious movements and a member of the Taizé ecumenical monastic community, which counts both Protestants and Catholics.