Why does the Church teach things that aren’t in the Bible?

Not everything that Jesus said and did is contained in the Bible. John’s Gospel verifies this: “There are also many other things that Jesus did, but if these were to be described individually, I do not think the whole world would contain books that would be written.” (Jn. 21:25) That means there are teachings that Jesus gave to his apostles that were not originally written down. We call these teachings Sacred Tradition or Apostolic Tradition.

The Catechism teaches us that the Gospel was handed on in two ways, Scripture—the written message of salvation, and Tradition—the oral, or spoken, message of salvation. “As a result the Church, to whom the transmission and interpretation of Revelation is entrusted, ‘does not derive her certainty about all revealed truths from the holy Scriptures alone. Both Scripture and Tradition must be accepted and honored with equal sentiments of devotion and reverence.’” (para. 82)

For example, the teachings about Mary as the Immaculate Conception and her Assumption come to us from Sacred Tradition, even though their foundations can be found in Scripture. Read more about Sacred Tradition in the Catechism, paragraphs 75-83.

Know your faith. Live your faith. Teach your faith.