The United Church of Christ inherited its instinct for inclusion from both halves of its 1957 merger, but nowhere is it stated more plainly than in its own 1959 Statement of Faith, which the denomination describes as a testimony of faith rather than a test of faith. No member and no local church is required to subscribe to it word for word in order to belong, a deliberate choice tracing back through the Congregational Christian Churches to New England Congregationalism's own refusal to bind conscience to any single creed.
That refusal had already produced one landmark before the UCC existed at all. On 15 September 1853, the First Congregational Church of South Butler, New York, ordained Antoinette Brown, making her the first woman ordained to the Christian ministry by a mainstream American denomination. Congregational ministers present were reluctant enough that the ordination itself was performed by a visiting Methodist, Luther Lee, but the local church's own authority to call and ordain whomever it judged fit for the pulpit went unchallenged, a principle the UCC would draw on again more than a century later.
In 1972 the Golden Gate Association in California ordained William R. Johnson, an openly gay candidate, the first such ordination on record in a mainline Protestant body. The General Synod took up the wider question of marriage in 2005, resolving in favor of equal marriage rights for same-gender couples years before most other American denominations, and years before the United States Supreme Court reached the same conclusion nationwide.