The Church is an organization that follows the Spirit of Light and wields considerable power in the human world. Most of the civilized world's education comes from the Church.
Under the leadership of the Archbishop, the Church has followed down the path of corruption, leading to the Crimson Scholar to be accused of being a demon to benefit the Central Nations.
A separate church called the True Church of the Light Spirit formed after the incident with the Crimson Scholar at the Lakeside Convent, leading to further conflict between the Winter Kingdom and the Central Nations.