You're right -- it is. Thank you for giving me the opportunity to clarify some murky beliefs.
First, let's address the myth that the Catholic church has already infallibly interpreted most or all of the scriptures. A good place to start is Providentissimus Deus (1893), Pope Leo XIII, Bishop of Rome. The Pope states that the number of passages which have not been infallibly interpreted is a "wide field."
"A wide field is still left open to the private student, in which his hermeneutical skill may display itself with signal effect and to the advantage of the Church. On the one hand, in those passages of Holy Scripture which have not as yet received a certain and definitive interpretation, such labours may, in the benignant providence of God, prepare for and bring to maturity the judgment of the Church; on the other, in passages already defined, the private student may do work equally valuable, either by setting them forth more clearly to the flock and more skilfully to scholars, or by defending them more powerfully from hostile attack."
A second good source is Divino Afflante Spiritus (1943), Pope Pius XII, Bishop of Rome. Here, Pope Pius XII expressly says that there are truths that remain undiscovered in the scriptures:
[L]let the Catholic exegete undertake the task, of all those imposed on him the greatest, that namely of discovering and expounding the genuine meaning of the Sacred Books. In the performance of this task let the interpreters bear in mind that their foremost and greatest endeavor should be to discern and define clearly that sense of the biblical words which is called literal. ...
Moreover we may rightly and deservedly hope that our times also can contribute something towards the deeper and more accurate interpretation of Sacred Scripture. For not a few things, especially in matters pertaining to history, were scarcely at all or not fully explained by the commentators of past ages, since they lacked almost all the information, which was needed for their clearer exposition. How difficult for the Fathers themselves, and indeed well nigh unintelligible, were certain passages is shown, among other things, by the oft-repeated efforts of many of them to explain the first chapters of Genesis; likewise by the reiterated attempts of St. Jerome so to translate the Psalms that the literal sense, that, namely, which is expressed by the word themselves, might be clearly revealed. There are, in fine, other books or texts, which contain difficulties brought to light only in quite recent times, since a more profound knowledge of antiquity has given rise to new questions, on the basis of which the point at issue may be more appropriately examined. Quite wrongly therefore do some pretend, not rightly understanding the conditions of biblical study, that nothing remains to be added by the Catholic exegete of our time to what Christian antiquity has produced; some, on the contrary, these are times have brought to light so many things, which call for a fresh investigation and a new examination, and which stimulate not a little the practical zeal of the present-day interpreter. (emphasis added by DallasMike)
Second, let's see what scriptures have actually been infallibly interpreted. Not surprisingly, the actual number of infallibly interpreted scriptures varies from source to source, but it is definitely quite tiny. According to R.E. Brown, “Hermeneutics,” New Jerome Biblical Commentary. (Prentice-Hall, 1990), 1146-65, the definitively interpreted passages are:
John 3:5 --- sacramental baptism (Trent)
John 20:23 --- sacrament of penance (Trent)
James 5:14-15 --- Anointing of the sick (Trent)
Matthew 16:16-17 --- Primacy of Peter (Vatican I)
John 21:15-17 --- Primacy of Peter (Vatican I)
Genesis 3:15 -- - Immaculate Conception (Pius IX, Ineffabilis Deus and Pius XII, Munificentissimus DeusAccording to Catholic Bible Apologetics, the infallible passages are:
John 3:5 --- sacramental baptism (Trent)
Luke 22:19 --- sacrament of the Eucharist
1 Corinthians 11:24 --- sacrament of the Eucharist
John 20:22-23 --- sacrament of penance (Trent)
Romans 5:12 --- nature of sin
James 5: 14 --- sacrament of extreme unctionOther sources, like the Catholic Dictionary, also define Matthew 28:19-20 (the Great Commission) as being infallibly interpreted.
I wish that the Vatican doesn't keep an Official List of Infallibly Interpreted Scriptures, but I guess that would make far too much sense.
You would do well to read further in the linked document:
But first it must be clearly understood whom we have to oppose and contend against, and what are their tactics and their arms. In earlier times the contest was chiefly with those who, relying on private judgment and repudiating the divine traditions and teaching office of the Church, held the Scriptures to be the one source of revelation and the final appeal in matters of Faith. Now, we have to meet the Rationalists, true children and inheritors of the older heretics, who, trusting in their turn to their own way of thinking, have rejected even the scraps and remnants of Christian belief which had been handed down to them. They deny that there is any such thing as revelation or inspiration, or Holy Scripture at all; they see, instead, only the forgeries and the falsehoods of men; they set down the Scripture narratives as stupid fables and lying stories: the prophecies and the oracles of God are to them either predictions made up after the event or forecasts formed by the light of nature; the miracles and the wonders of God's power are not what they are said to be, but the startling effects of natural law, or else mere tricks and myths; and the Apostolic Gospels and writings are not the work of the Apostles at all. These detestable errors, whereby they think they destroy the truth of the divine Books, are obtruded on the world as the peremptory pronouncements of a certain newly-invented "free science;" a science, however, which is so far from final that they are perpetually modifying and supplementing it.