Tucked away in the sprawling mountains of Gimje, South Korea is one of the country's oldest churches. The building is designed in a traditional Korean architecture popular in the late-19th century.

Established in 1905, Geumsan Church was built with the help of U.S. missionary Lewis Tate, who was affiliated with the U.S. Southern Presbyterian Church. He and six others are credited with spreading the gospel throughout the southwestern regions of the Korean Peninsula.

The floor creaks as you walk into the church's worship chamber. The church's layout is uniquely built in an ‘L'-shape, reflecting the customs of the time.

When Western influences first arrived in Korea, Confucian ways dictated social behaviors. That meant men and women were not allowed to worship together. To accommodate this, the church's design would allow both genders to attend service together yet adhere to strict Confusion norms.

The current head pastor of Geumsan Church is Kim Jong-won. He believes church elders built the church in this way to foster an inclusive atmosphere where all could worship.

“In Confucian teaching, there is a saying that boys and girls shouldn't sit together after the age of seven. At the time, it was difficult for men and women to face each other and attend church services,” Kim said.

Christianity is the most popular religion in South Korea, along with Buddhism and other shamanistic beliefs. Roughly 3 in 10 people identify as Christians, and of that, three-quarters are Protestants and the remaining Catholics.

The number is significant, considering just one percent of the population was Christian at the beginning of the 20th century. Now, no other country produces more missionaries in the world except for the United States.

But recent government data shows that the number of Christians in the country are declining. In fact, a growing number of younger South Koreans are moving away from the church.

“I don't think it's an issue of younger people losing interest. Rather, I think it's the result of the church failing to embrace youngsters in the current environment properly. That's why the most urgent task for the church is to create a spiritual environment, a spiritual mood to allow youngsters to come and freely praise the Lord,” said Pastor Kim.

South Kore has seen several high-profile cases of corruption involving Christian pastors at so-called megachurches over the years. Experts believe many have been turned off by this exposure.

But Kim believes it's only a select few, and that the true meaning of God's word remains constant. He also believes there can be a peaceful co-existence and harmony among the various religions in the country.

“Some have been blinded by the changing times and forgotten the true meaning of the gospel. It's true some have not lived a righteous life under the gospel. But although times may have changed, the essence of the gospel doesn't change,” Kim said.