Final answer:
Calvin Coolidge's religious faith was Unitarianism, a sect that emphasized the importance of human reason and the inherent goodness of humankind.
Step-by-step explanation:
Calvin Coolidge's religious faith was Unitarianism. Unitarianism is a sect based on the importance of human reason, and it stressed the inherent goodness of humankind and the oneness of God. The Unitarian church was most popular in New England and appealed to the elite of society. Coolidge's belief in the Puritan work ethic aligned with the Unitarian emphasis on hard work and moral lifestyle focused on piety.