I love sola Scriptura as much as the next guy. What I mean is, I love the idea that reasonably intelligent people should be able to interpret God’s Word and come to agreement on what God is saying through it.
It’s such a good-sounding idea that I did believe it for quite a while and felt that the important things were obvious and the things that weren’t must not be that important. Take homosexuality for example. Easy! St. Paul condemns homosexuality in a few places, so it must be wrong.
And lots of my Protestant friends believe this way, but I also have Protestant friends who don’t see it so cut-and-dried. They argue that the verses seemingly against homosexuality should be classed with those about women being silent and wearing head coverings. They also claim that the verses can be reasonably interpreted not so much against homosexuality per se but against certain other aberrant types of behavior.
Since the Bible alone is the sole infallible rule of faith, it’s one interpretation against another.
Here is where sacred Tradition comes in with a royal flush and takes all the money.
When you ask me as a Catholic whether homosexual acts are sinful, I can point you to the Church and her teachings. That includes the biblical verses but backs them up with interpretations from the Church Fathers, from papal encyclicals, and Ecumenical Councils.
The history of the Church demonstrates her unchanging teaching that marriage is for one man and one woman and that same-sex acts are immoral. I can point you to the Theology of the Body and arguments made by greats like St. Thomas Aquinas that draw from divine law and also natural law.
In short, I can point to sacred Tradition as a credible witness to divine truth.
For many sola Scriptura Protestants, arguments outside of the Bible itself carry little to no weight. Who cares what the Church taught through the centuries–this is the same Church that came up with prayers to the saints, purgatory, the Mass, and Marian dogmas! And because under Protestant theology grace eradicates nature and our natures are so corrupted, divine revelation–as known through the Bible alone–trumps completely any arguments that we might make through the natural law.
Thus the Catholic Church makes the Faith knowable with conscience-binding certainty. We aren’t left wondering whose opinion is right about such-and-such moral or theological issue. We have more than a he-said, she-said situation. We have the divine guidance of the Church through the centuries in her teachings, explaining the Faith and clarifying issues when necessary so that there is no doubt as to what divine revelation consists of.
For a real example of how this can play out in people’s lives, see this moving story of one man’s struggle with same-sex attraction, the Bible, and his Christian faith,