Buddhism

Buddhism first arrived Korea in the A.D. 372 of the reign of King Sosurim of the Goguryeo Kingdom . Afterwards, Buddhism exerted a strong influence in the Baekje Kingdom and Silla Kingdom . Seokguram Grotto and Bulguksa Temple are selected by UNESCO as World Heritage sites, are Buddhist creations from the Silla Kingdom . The nation's valuable Buddhist heritage abides in sculptures, buildings, handicrafts, paintings, etc.

Catholicism & Protestantism

Christianity confronted the basic ethics of Joseon society, it's believers were subject to persecution in the early years, but as Christians took an increasingly active role in the anti-colonial struggle against the Japanese and churches promoted more educational opportunities, Christianity gained acceptance. There are about 25% of Korean population is Christian. Catholicism first came to Korea as a western scholarly pursuit. There are more than 2 million people go to the Catholic Church in Korea now.

Confucian

Koreans probably believe Confucianism the most in the world. They believe that Confucianism is not actually a religion, but a code of moral principles. For instance, you have to state different words for the same thing depending on people's status and their age. That's why Koreans always ask about your age first when they first meet you, and then they will call you with the proper title. Even in the family or friends, they usually would have to address each other in a different way depending on the age.