What in Catholic tradition is sacred?
“Apostolic Tradition” (Catechism of the Catholic Church 75-76) can refer both to written Tradition (Scripture) and unwritten Tradition, or it can refer to either one alone.
But I infer you’re referring to unwritten Tradition, also commonly known as Sacred Tradition, which is distinguished from Sacred Scripture. Unwritten Tradition includes the apostles’ teaching, liturgical practice, and institutions such as apostolic succession. So we know that the seven sacraments are sacred, as well as the apostles’ teaching (Acts 2:42), and also institutions like the office of bishop, which of course is intimately related to the celebration of the sacraments.
And, as the Church provides, “The Church, in her doctrine, life and worship, perpetuates and transmits to every generation all that she is, all that she believes” (CCC 78). So the Church’s living and sacred Tradition would also extend to the Church’s authentic devotions and faithful preaching. So, in one way or another, everything in sacred Tradition is sacred for one reason or another.
For more information see our tracts on “Apostolic Tradition” and “Scripture and Tradition.”