Donghak's teaching, In-nae-cheon, means "humans are divine." It is said, "When humans were formed, God's blessing was required for their formation." Donghak's Sincerity, Respectfulness, and Faithfulness is based on believing in God, respecting God, and practicing His teachings with utmost sincerity. These are key to implementing In-nae-cheon. On the other hand, the Three Essential Attitudes in Daesoon Thought, also Sincerity, Respectfulness, and Faithfulness, appear in a religious sense. These can be distinguished from Sincerity, Respectfulness, and Faithfulness in the Donghak moral sense. Sincerity, Respectfulness, and Faithfulness in the context of the Three Essential Attitudes in Daesoon Thought goes beyond moral awareness, and calls for belief in God as the Absolute. Accordingly, Sincerity, Respectfulness, and Faithfulness in this context, that of Daesoon Thought, aims at the realization of an Earthly Paradise wherein God's will can be achieved. Humans participating in the construction of Earthly Paradise value the practice of Sincerity, Respectfulness, and Faithfulness. In Daesoon Thought, it is said that when one exerts sincerity, respect, and faith in God (Sangje), all the blessings and fortune of the Later World, even those of longevity, will be endowed through transformation via effortless action (無爲而化). Accordingly, Sincerity, Respectfulness, and Faithfulness in the context of the Three Essential Attitudes in Daesoon Thought is based on God's descent into the world and His Reordering Works of Heaven and Earth (天地公事). This is a religious faith that worships Sangje and is based on the doctrinal dimension of 'guarding against self-deception (毋自欺)' and the philosophical dimension of Sincerity, Respectfulness, and Faithfulness in the context of the Three Essential Attitudes in Daesoon Thought. Donghak's In-nae-cheon and the Three Essential Attitudes in Daesoon Thought can be compared and analyzed. Therefore, in order to clearly compare and analyze the moral significance of Donghak history and the religious meaning of Daesoon Thought, Roderick Ninian Smart's method of religious phenomenology can be actively used. In this way, the ethical and legal dimensions of Donghak's In-nae-cheon and the doctrinal and philosophical dimensions of the Three Essential Attitudes in Daesoon Thought can be compared and analyzed. From this style of research, it can be concluded that the realization of commonly shared spirituality can be an opportunity for greater human dignity.