Choe Je-u expressed his central insight in the phrase si cheonju, bearing the Lord of Heaven within. He did not mean that a person is God, and he did not mean that God is remote. Haneullim, the Lord of Heaven, is understood as present in every person and in all things, so that serving other people is the way in which God is served.
The second leader, Choe Si-hyeong, drew the practical conclusion in a formula usually rendered as treating people as heaven, and applied it in ways that were socially explosive in nineteenth-century Korea. He taught that a child being beaten is heaven being beaten, and that a daughter-in-law at the loom is heaven at work. The movement took in slaves, the low-born, women and widows permitted to remarry, and treated the caste distinctions of the late Joseon order as simply false.
The third leader, Son Byong-hi, condensed the teaching into innaecheon, man is heaven, the phrase by which Cheondoism is now best known. Scholars disagree over how far that shifted the religion from theism towards a humanistic immanentism, and Cheondoists themselves have taken different positions on it at different periods.
Practice is deliberately plain, and there is no priesthood in the sacrificial sense. The core devotion is a twenty-one character incantation recited daily. Members keep a rite using a bowl of clear water, cheongsu, set out at a fixed hour, and a practice of silent report to the divine before acting. The scriptures are the Donggyeong Daejeon, in classical Chinese, and the Yongdam yusa, hymns in vernacular Korean, both from the founder.