The basic rule of thumb to understand in Catholic/Protestant conversations is that it is not the case the Catholics rely on Sacred Tradition and Protestants don’t. Rather, Catholics rely on Sacred Tradition and know they do, while Protestants rely on (parts) of Sacred Tradition and (usually) don’t know they do.
So, for instance, nowhere in the text of Scripture is it made clear that Christian marriage *must* be monogamous or that the Holy Spirit is a person, much less the Third Person of the Blessed Trinity, consubstantial with the Father and the Son. You will look in vain for instructions in Scripture on how to contract a valid marriage (unless you buy this list of “Top 10 Ways to Find a Wife, According to the Bible):
10. Find an attractive prisoner of war, bring her home, shave her head, trim her nails, and give her new clothes. Then she’s yours. – (Deuteronomy 21:11-13)
9. Find a prostitute and marry her. – (Hosea 1:1-3)
8. Find a man with seven daughters, and impress him by watering his flock.- Moses (Exodus 2:16-21)
7. Purchase a piece of property, and get a woman as part of the deal. – Boaz (Ruth 4:5-10)
6. Go to a party and hide. When the women come out to dance, grab one and carry her off to be your wife. – Benjaminites (Judges 21:19-25)
5. Have God create a wife for you while you sleep.-Adam (Genesis 2:19-24)
4. Kill any husband and take his wife. -David (2 Samuel 11)
3. Cut 200 foreskins off of your future father-in-law’s enemies and get his daughter for a wife -David (I Samuel 18:27)
2. Even if no one is out there, just wander around a bit and you’ll definitely find someone. -Cain (Genesis 4:16-17)
1. Don’t be so picky. Make up for quality with quantity. – Solomon (1 Kings 11:1-3)
….which doesn’t really help much). The fact is, the Bible says “Marriage is good” but gives us not one word of instruction on how to do it. And yet, of course, Protestants all over the world get married, believe in God the Holy Spirit, and have but one spouse because, as James Dobson says, God’s plan is one man and one woman. How do they do this when Scripture is so unclear? They accept Sacred Tradition percolated to them from the Catholic Church through the Protestant tradition. It’s the same way they know that the books of the Bible they accept are supposed to be books of the Bible. It’s the same way they know that public revelation closed with the death of the apostles even though Scripture is completely silent on the matter. Retention of Catholic Sacred Tradition fragments has kept Protestantism in such sanity as it possesses. So when the Bible Answer Man appeals to “historic Christianity” in understanding what the Bible means, that’s typically a good thing. He’s appealing to Sacred Tradition and agreeing with the Church. Eupocrisy in action!
However, in those places where Protestantism attempts to reject Catholic teaching, the narrative suddenly and wrenchingly changes. Suddenly, the demand is made for nothing less than an explicit proof text from the Bible. If a thing is condemned by the Church, but permitted by the Protestant (say, gay marriage) the demand is for an explicit text condemning it (“Show me where Jesus said one word about gay marriage!”). If a thing is allowed by the Church but condemned by the Protestant, the demand is for an explicit text permitting it. So, for instance, we get demands like:
Because I am a Christian who prefers to get my instruction from the Bible only, your use of another source doesn’t help the argument you’re making – for me anyway. In your Romans quote Paul is asking brothers who are alive to pray, through Jesus. Where in the Bible do you find anyone asking us to pray to dead people?
Note how the terms have suddenly shifted. It’s no longer good enough to say, “here are biblical passages which, taken together, point to the reality that the Holy Spirit is a Divine Person even though there is no text that says “The Holy Spirit is the third person of the Trinity”.
No, arguing from obvious implication is out the window. Only direct, explicit testimony and instruction in legally watertight language will do. The Protestant who want to permit abortion points out that there is no unequivocal commandment in either the Old or New Testament saying “You shall not have an abortion” and evinces absolutely no interest in the way in which the texts we do have were universally read by the early Church. Likewise, the Protestant who dogmatically rejects prayer to the saints simply ignores you if you point to the fact that the dead (like Moses on the Mount of Transfiguration) are aware of what’s happening on earth and that we are told that “we shall be like Christ” (who intercedes for us) and that the Body of Christ is One (not split in two by death) and that the early Church understood all this to imply that we can ask prayers of the dead just as we ask them of the living….
No dice. Suddenly, depending on the Protestant, the terms become “Unless the Bible explicitly says, ‘No gay marriage or abortion’ or ‘Ask prayers of the dead and pray for the dead’ then the Catholic teaching is ‘unbiblical’”. (Of course, the word “Bible” is not unbiblical–even though it also never appears in Scripture–because the word “Bible” is another fragment of extra-biblical Christian tradition acceptable to Protestants.)
You get the picture. All the various forms of Protestantism have this (and only this) one feature in common. They may differ on Mary, or baptism or the divinity of Jesus or even the existence of God (if you include Unitarians as a particular robust form of Protestant thinking). But they all agree on this: they erect semi-permeable membranes in which some (but not all) pieces of Sacred Tradition are allowed through (different bits for different groups). Those that are allowed through are called “the witness of historic Christianity” or “the clear implication of Scripture” or “the obviously reasonable position”. Those not allowed through are called “human tradition” or “myths” or “the unbiblical teachings of Rome” (even when they are the obvious testimony and practice of all the apostolic communions in the world since the beginning of the Church.) Finally, to these filtered-in elements of real apostolic theological and moral teaching are stapled sundry human traditions like sola scriptura or some theory about predestinarianism or the “perspicuity of Scripture“* or the need to speak in tongues or (in the past) the curse on Canaan as a biblical basis for American chattel slavery or (more recently) the glories of homosexuality or abortion (as I say there is enormous diversity).
Of course, as history goes on and at least some sectors in Protestantism allow the centrifugal force of the worship of Private Judgement to move them further and further from both Sacred Tradition and (inevitably, given the logic) from Sacred Scripture as well, you reach a point where appeals to Scripture don’t matter since Scripture is, after all, simply the written aspect of Tradition. Sooner or later, it occurs to people trending away from acceptance of apostolic tradition to ask, “If I’ve rejected everything else the Church says, why should I care about its ‘holy’ writings? I can find a hundred German Protestant theologians who say of the supposed ‘word of God’ what I’ve been saying of ‘sacred tradition’ all along.”
For now, many Evangelicals still retain a deep reverence for the sacred writings (though the Emergent Church Movmement is already starting to give some signs that the itch to deconstruct will wreak enormous damage among those who come to clearly face the choice between the pole in Protestantism that seeks the apostolic faith and the pole that seeks to keep deconstructing until nothing, including Scripture, is left).
For those still in this betwixt and between stage, who reverence Scripture and have this conflicted grasp of an Apostolic Tradition coming to them through a semi-permeable membrane, what is needed is a paradigm shift, and I’m happy to help assist in that:
*Speaking of the theory of the “perspicuity of Scripture” (a notion directly denied, not only by 2 Peter 3:15-16, which says of Paul’s writings that “in them there are some things hard to understand”, but by everybody who has ever attempted to read the book of Revelation, starting with Martin Luther who wryly observed that “a revelation ought to reveal”), I once watched an absolutely hilarious discussion drag on for dozens and dozens of posts, in which a Reformed guy labored to precisey define what “perspicuous” meant. One of the most hilarious moments in unconscious irony I have ever seen.
For more details on how Sacred Tradition is semi-permeably used in Evangelical circles, see this excerpt from By What Authority?.