Confucian values permeate most of Korean society. And Catholicism, before it became an object of belief, was an object of study for Confucian scholars. When Catholicism finally took root in Korea, it was not merely a transplant of a foreign culture to Korea that was to influence the culture of the country but was in turn influenced by the Confucian culture.
Confucianism is covered by the 3rd article in a series on Catholicism and Other Religions, appearing in the Peace Weekly. The Jinsan incident in 1791 resulted from a refusal of the Korean Catholics to follow the Confucian mourning rituals, worsening the dispute between Catholics and Confucians.
There have been two approaches suggested to deal with the dispute: accommodation with Confucianism, the Jesuit approach in China, or respond to the difficulties by a strict adherence to traditional Catholic teachings. The difficulties between the two religions are briefly noted in the article. The Confucian idea of heaven would be similar to the Christian understanding of the God of the Old Testament; it's both a transcendent and immanent idea of heaven. In early Confucian writings, a word meaning the king of heaven was used, with some implication of the existence of a supreme personal God.
There is a difference in the way Confucians see the creation; it is not a creation from nothing, everything begins with the human and ends with the human. Everything is subjective, positive and optimistic. We are given, they believe, a mandate from heaven that can be attained by the practice of virtue.
The ultimate virtue for the Confucian is benevolence (note its Chinese character above left), that quality of goodwill toward others that can and should exist in any personal relationship. This understanding is similar to 'love' in Christianity. However, the approach to fulfillment in life in each religion is different; in Confucianism, fulfillment is self-achieved while in Christianity, fulfillment, that is, sanctification, can't be achieved only by personal effort.
For a Confucian, there is not much interest in creation apart from humanity. Their interest is in living a life of natural goodness that can be expanded by self-actualization; that is their aim in life, their salvation. The Confucian wants to cultivate his moral sensitivity so that he will be able to act correctly and bring peace to others. All that the Confucian aims for, the Christian finds in Christ.