Tidbits from the Catholic Encyclopedia on the job the infallible church has done in 2000 years of infallible biblical interpretation:
“The Catholic commentator is bound to adhere to the interpretation of texts which the Church has defined either expressly or implicitly. The number of these texts is small, so that the commentator can easily avoid any transgression of this principle.”source
"...the Holy Fathers, we say, are of supreme authority whenever they all interpret in one and the same manner any text of the Bible, as pertaining to the doctrine of faith or morals; for their unanimity clearly evinces that such interpretation has come down from the Apostles as a matter of Catholic faith...This unanimity is not destroyed by the silence of some of the foremost Fathers, and is sufficiently guaranteed by the consentient voice of the principal patristic writers living at any critical period, or by the agreement of commentators living at various times; but the unanimity is destroyed if some of the Fathers openly deny the correctness of the interpretation given by the others, or if they explain the passage in such a way as to render impossible the explanation given by others."
So there you have it: in 2000 years the infallible church took care of a few scripture passages. Great job.
The infallible church also looks to the unanimous consent of the fathers for some help in figuring out the Bible. Let’s try this for some ‘certainty’. We’ll start with the Fathers’ comments on Matthew 16:18- “The Patristic Exegesis of the Rock of Matthew 16:18.” After reading this link, the line above from the Catholic Encyclopedia really has an interesting ring to it: "...the unanimity is destroyed if some of the Fathers openly deny the correctness of the interpretation given by the others, or if they explain the passage in such a way as to render impossible the explanation given by others."