What would you do if someone asked you to dip your hand into the Mississippi River in New Orleans and take a big drink? Would you do it? Not only would you not drink the water, you would probably think the person who asked you to drink it was crazy or just plain mean. In a spiritual sense, this is exactly what Catholic theologians are asking people to do.
In the Catholic Church, Scripture and Sacred Tradition go hand in hand. The Catholic Church teaches that both Scripture and Tradition are of apostolic origin and, therefore, equal in authority. To make their case, Catholic theologians and apologists will direct folks to a time in church history when there were no written doctrines or accounts of Christ’s life and teachings, only oral testimony, i.e., tradition. The logic derived from this is that since oral tradition was authoritative in the ancient church, and the written apostolic source (the New Testament) cannot possibly contain all that the apostles taught, it stands to reason that oral tradition remain authoritative for Christians.
The problem is they never get specific about the traditions. What exactly did the apostles teach orally that we cannot glean from Scripture? Did they teach that Mary, the mother of Jesus, remained a virgin her entire life, or that the blessed bread of communion transubstantiates into the glorified body of Christ when blessed by a priest? These and a host of other so-called “Sacred Traditions” of the Catholic Church are the spiritual equivalent of what makes the Mississippi River undrinkable.
Hundreds of years of developing doctrines have flowed into the once pure stream of Christian truth poisoning it and leaving it non potable. But like a river, the pollution of false doctrine only occurs downstream from its source. And having the ability to return to the source and drink the pure doctrine found there, enables us to know what the doctrine should look like. So it is for us to recognize from the word of God, our source of pure doctrine, what is truth and what is not truth, thus permitting us to filter out the impurities of false doctrine in our own time.