We Catholics often talk about the early Church Fathers, referring to them to support Church practices that aren't necessarily so clearly stated in the Scriptures. But the Church Fathers' writings are not inspired - they are not on the same level as the Scriptures themselves, which is the Word of God written.
But the Church Fathers were the recipients of the faith, passed down to them from the Apostles. So St Ignatius of Antioch learned from St John the Evangelist (the Apostle) what he taught about Church life.
It might be, as I recently heard Patty Bonds describe it, (though the analogy is not perfect - analogies never are) like the game of Telephone. If one wants to find out the truth about what was first said, the person to ask is someone at the front of the line.
It might be, as theologians so often do with texts, that more weight is placed on the earlier texts (in this case, the earlier texts are persons, closer to the actual teaching of the Lord and the Apostles). They want to find as early a text as possible, believing that text to be closer to the original autograph.
It might be both of those things, but it is also more. We turn to the early Church Fathers because their writings, even if they are not inspired, open for us a window into how the early Church operated, what it taught and believed from its inception.
So let's say, as an example, that we learn about some tradition begun in A.D. 1352 in the Church. That is a less compelling truth - though it still may be a truth - than if we know the Church was practicing and believing something at the turn of the first century - as we find in the Didache, and in the writings of St Clement of Rome and St Ignatius of Antioch. These are precious and insightful documents not just because they contain truth in them about God, but because they shed light about what and how the Church believed and practiced in the generation that immediately followed, the generation taught by, the Apostles.
Some people want to disregard it all, believing that nothing is authentic that is recorded outside the Scriptures. This view of Church history (history in general) falls short in a number of ways. First, the Scriptures themselves never give themselves that kind of exclusivity. Second, the Scriptures did not spring up out of a vaccuum. Third, the canon of the Scriptures was decided upon by the Church in the fourth century. So if you believe the Church went off the rails early, you are trusting in the infallibility of letters that were decided upon by a corrupted and fallible Church. In other words, a fallible collection.
Such a belief undermines our very faith.
It should also be obvious that some things that Christ and the Apostles taught and practiced were not placed in the Scriptures (John says so at the end of his gospel, if you don't accept the common sense of such a statement). That doesn't make the teachings or practices unbiblical (meaning contrary to revealed-truth-written), but it does make them extra-biblical (outside revealed-truth-written). And Protestant traditions themselves are full of extra-biblical practices, from child dedication to order of worship to music choices to church buildings. The list goes on.
For me, therefore, the early Fathers are compelling. When St Ignatius and the Didache speak of the Eucharist as the actual Body and Blood of our Lord and as true sacrifice (as the Scriptures do), it ought to make contemporary believers - believers who have been taught that Communion is merely a symbol (a belief promoted by Zwingli in the sixteenth century) - stop in their tracks and re-evaluate what they're reading, and, I hope, what they're believing.
When the early Fathers talk about baptism and faith together saving us (as the Scriptures do) - those who believe it is merely a symbol ought to re-evaluate how and why they read the statements about baptism in the Scriptures (baptism now saves you, baptism washes away your sins, baptism unites you to Christ, etc.) as being metaphorical rather than literal.
The early Church Fathers, though they are not the Scriptures, are invaluable to us. They allow us to see how the Apostles understood and interpreted their own writings, the Scriptures. And they allow us to peer into the life of the early Church - how it was and how it is meant to be.