One of the key principles of Protestantism that distinguishes it from Catholicism is sola scriptura, or “Scripture alone.”
Though it’s interpreted differently among Protestants, it generally means that the Bible is either the highest or sole authority for Christians, trumping ecclesiastical authority and tradition.
The Catholic Church rejects sola scriptura, teaching instead that the Word of God is passed down in both written Scripture and oral Tradition, and that the Church’s magisterium is guided by the Holy Spirit to definitively and authoritatively interpret the Word of God for Christians.
Here are three major problems with sola scriptura:
1) The Bible rejects it
Where do Protestants get the idea that the Bible alone is the highest authority for Christians? Is this taught anywhere in the Bible?
Actually, no. Pretty much all of the verses to which Protestants usually point to answer this question indeed speak highly of the authority of Scripture and its importance for the people of God (e.g. Psalm 119, 2 Timothy 3:16-17, et al), but none of them say that the Bible alone is the only authority.
No only that, but the Bible upholds the authority of oral tradition alongside Scripture in contradiction of sola scriptura. In 2 Thessalonians 2.15, St. Paul writes: “So then, brothers and sisters, stand firm and hold fast to the traditions that you were taught by us, either by word of mouth or by our letter.” St. Paul is saying that his teachings are authoritative, whether he gave them by speaking (oral tradition) or writing (Scripture).
2) It can’t explain where we got the Bible
If the Bible is the only authority for Christians, then where did Christians get the Bible in the first place? Who determined what books should be in the Bible?
God did not hand Christians a fully compiled Bible out of the sky. Rather, God inspired many different writers over the course of many centuries to write the various books of the Bible. And then God inspired the Catholic Church, wielding apostolic authority and relying on oral tradition of what books are inspired, to definitively compile the biblical canon in the 4th century.
This means that the biblical canon itself depends on the very authority of oral tradition and ecclesiastical authority that Protestants reject.
3) It doesn’t work
The Bible has to be interpreted. Even when people think it’s clear what the Bible is saying, they are interpreting it. The problem is different Christians often interpret the Bible in contradictory, mutually exclusive ways. When that happens (and it happens constantly), how does the Christian church settle disagreements and safeguard the Gospel truth God has revealed in Jesus Christ?
Because if Christians can’t agree on what the Gospel is, they can’t fulfill their responsibility to preach it.
Sola scriptura offers no way out of these disagreements, except for Christians to split and go their separate ways – hence, myriad denominations. But this is a problem, too, because the Bible teaches that division among Christians is a sin (cf. 1 Cor 1.10ff, et al)!
The way out of this problem is the way of the very Catholic Church that Protestants reject, the way dating back to the early Church established by Jesus: Christ gave the Apostles authority to teach and govern the Church, authority which they passed on to bishops all the way to the present day in succession. This apostolic authority doesn’t trump the Word of God (passed down in written Scripture and oral Tradition), but rather is guided by the Holy Spirit to safeguard it for every generation.