Sunday in Seoul -- As dusk turns to dark in this capital city, the skyline glitters with more than the urban lights of office towers and apartment blocks. From the hills that define Seoul's topography and neighborhoods it is easy to spot lighted electric crosses. They are among the most visible reminders of just how deeply Christianity shapes South Korea.

Somewhere between a quarter to a third of South Korea's nearly 50 million people are estimated to be followers of a Christian denomination, a third of them Roman Catholic and the remainder Protestant. Another quarter of the population are Buddhist and many of the rest followers of Confucian precepts. In Asia, only the Philippines counts a higher percentage of Christians.

From this country's conservative social mores to its often conservative politics, the Christian influence is pervasive.

And, especially on Sundays it is on colorful, enthusiastic and vivid display. Nowhere more so than the Yoido Full Gospel Church, a denomination that asserts a South Korean membership of 750,000 and more than 600 missions overseas, most set up to reach the 2 million Koreans and Korean-Americans living in the United States.

Established in a complex of office buildings in one of Seoul's more posh neighborhoods, the church crams its Sunday congregants into 12 hours of back to back services, most in the main sanctuary that seats 12,000 worshipers.

Our group of editors and producers was invited to an afternoon youth service, a boisterous gathering that was part rock concert and part revival meeting, one that would have many elements of familiarity to Americans attending megachurch or gospel services in the United States. The singing, with a full dress choir on the side and a rock band in front and the audience following lyrics scrolling on two big screens on either side of the pulpit was full of verve and emotion. The lead guitarist sometimes resembled Mick Jagger, jumping up and down on the altar platform. The congregation, from teenagers to 30somethings, sang and swayed with the music, some with arms upheld in reverie and devotion.

Amid the celebration, the leaders make clear their serious purpose -- to spread the Gospel as far and wide as possible.

"Our church emphasizes the word and manifestation of the Holy Spirit," said Assistant Pastor Yong Joon Kim, who recently returned to the main church after serving six years in Chicago. Whether that manifestation stretches across the 38th parallel to North Korea is a slightly more complicated matter. The church's leader, Pastor David Cho, had, until recently, written off the North as hopelessly lost to the communists, but now is reaching out, perhaps anticipating the regime's collapse. The church is expecting soon to start work building a cardiac clinic in the North, having won a concession of keeping a chaplain on the premises.

The role of this and other churches in South Korea is sometimes indirect and opaque. Though many high level politicians are practicing Christians and keep their faith a private matter, others are more open. In the upcoming presidential election, the conservative party candidate Lee Myung-bak is a Presbyterian and has not hidden his religious convictions. In return, he can expect the backing of many conservative evangelicals.

Yet devotion and politics are not all on the right. For years, Seoul's Catholic Cardinal Archbishop Kim has been a symbol and bulwark of democracy and human rights as the country emerged from decades of military dictatorship. And former President Kim Dae Jung, the secular symbol of both the democracy struggle and reconciliation with the North, also is a practicing Catholic.

It was at Seoul's Anglican Cathedral that I was introduced to Lee Jae-jung, the Unification minister of the current liberal government, which has been pushing for more collaborative measures with the North. The cathedral in central Seoul, built in the shape of a cross, could be a patch on Old England with one critical distinction: its pews are jammed. The singing was in full voice, Korean words matched to the mainly European compositions of the Anglican hymnal. (Perhaps it is just a matter that Koreans like to sing, but their language seems tailor-made for spiritual and other music). The liturgy was familiar to an American Episcopalian even if the words were not. And like Anglican churches everywhere, the members are split on the issue of ordination of gay bishops and blessings of same-sex unions that threatens to tear the worldwide church apart.

But from its once firm opposition to such a move, this church is now more involved in debate and is seeking a compromise and dialogue, at least according to one parishioner, admittedly on the liberal side, Key Jun, an academic who studied at SUNY-Buffalo in the 1980s. His family personifies South Korea's religious spread. His father is Confucian, his mother Buddhist, his sister Roman Catholic and his brother Methodist.

To a preacher and a parishioner on opposite sides of modern theological and ideological divides, I posed the same question: How did Christianity gain such a foothold in an Asian country that never experienced Western colonialism? The historical answer is pretty straightforward. The Jesuits coming down from China in the late 1700s represented the first wave. The Protestant missionaries came next in the late 1800s.

But the Anglican parishioner Jen added a slightly different interpretation to some of that history. Even citing the church's location next to the British and other embassies on prime real estate, he related the expansion of Christianity to the collapse of the ancient Korean monarchy by the turn of the 20th century and contest among Western powers for spheres of influence there and in the rest of Asia.

Pastor Kim had two more direct answers: Unlike many other nations, Korea always had a concept of one God, in the Korean name of Hanahnim. What the missionaries and Christianity offered, he said, "Jesus is the way to God. We could easily understand that concept."

"We have been through so many trials and tribulations over 5,000 years, so many wars and fighting. So when the Christians came here and talked about peace and love and harmony, we were so excited about that and accepted the concept of God and a relationship with Jesus."

A discussion in further detail is better left to historians and theologians. But to a newly arrived visitor, these observations offer some sliver of insight as to why in this land of mammon (now the 10th or 11th richest in the world, depending on who's counting) and modernity (describing itself as the most high tech on the globe), so many crosses glitter in the evening landscape.

-- By Michael Mosettig, NewsHour with Jim Lehrer