In its two-thousand-year history, the Catholic Church remains an unchanging yet developing entity. Since the church's infancy, Catholic theologians have referenced the "deposit of faith," which in early years referred to the written or orally revealed doctrines that formed the backbone of church teaching.

Through the centuries, the definition came to be understood as the word of God, delivered through Jesus Christ and passed on to his apostles. Still, the deposit included both oral and written traditions and provided moral direction.

The Second Vatican Council brought about many...