Truth is saying of what is, that it is and of saying what is not, that it is not. In other words, truth points to reality and we should strive to live according to truth because we should strive to live according to reality. Since we are finite beings with imperfect knowledge, we have to constantly reassess what we think is true, discarding what turns out to be false and amending ourselves when our earlier grasp of the truth turns out to be inadequate. If someone makes a claim, but we do not know whether it is true or false, we need to find out before accepting or rejecting it—we can’t just rely on their say so.
(Some people, despite their claims, are not reliable sources of truth)
When you read that, it seems obvious. But human fallibility makes it difficult. Some people are liars. Some mistakenly think a falsehood is true. Sometimes people misinterpret the message and think their reasoning about these misinterpretations are truth. It is true we can’t assume that the person who speaks falsely is malicious, but just because a person says something does not make it true.
This realization is especially important when people say things that impact how we view the world. Just because an anti-Catholic attacks membership in the Church because they claim we do not follow Scripture, or just because a radical traditionalist attacks what the Pope says today on grounds that he “contradicts” what earlier Popes had to say does not make their claims true. If one wants to refute a worldview, they have to show that they accurately understand what the teaching authority (magisterium) of the Church holds compared with what others claim she holds. The brilliant 19th century work A Manual of Catholic Theology tells us:
The heirs of the Apostles have the right and duty to prescribe, promulgate, and maintain at all times and in behalf of the whole Church the teaching of the Apostles and of the Church in former ages; to impose and to enforce it as a doctrinal law binding upon all; and to give authoritative decisions on points obscure, controverted, or denied. In this capacity the Church acts as regulator of the Faith, and these doctrinal laws, together with the act of imposing them, are called the Rule of Faith. All the members of the Church are bound to submit their judgment in matters of Faith to this rule, and thus by practising the "obedience of Faith" to prove themselves living members of the one kingdom of Divine truth.
Scheeben, Matthias Joseph (2015-03-26). A MANUAL OF CATHOLIC THEOLOGY: Based on Dogmatik (Complete in Two Volumes) (Kindle Locations 1412-1416). Lex De Leon Publishing. Kindle Edition.
So, if the anti-Catholic, the radical traditionalist, the modernist dissenter or other person tries to attack part of the Catholic faith with the intention of changing our view of reality, the first question is, whose interpretation of Church teaching do we trust to be most accurate?
- The individual who accuses the Church of saying X?
- Or the Church under the authority of the present Pope and bishops in communion with him?
Hint: The answer is #2. Even if one rejects the authority of the Catholic Church as having the authority to teach, it is common sense to ask a person whether we have understood them, not to assume that our interpretation is error-free. If we’ve misunderstood what the Church has said, the end result of our reasoning is going to be worthless. But people don’t try to find this out.
For example, anti-Catholics make all sorts of assertions about what we believe and pull out Bible verses to “contradict” us. But they never ask whether they have understood us accurately or whether they have misapplied Scripture on the rare occasion when they do understand us rightly. Radical traditionalists assume that a difference in tone from one era to the next “proves” a change in teaching. But the question to ask is whether the Church today is really condoning what she used to call sinful or whether she is merely speaking about changed tactics or changed circumstances while still holding to the underlying belief.
So, before we accept their claims as true and try to live according to them, we have to see if they are true. Does the Church teach the same as what her critics allege she teaches? But we can’t just rely on someone’s claim that there is a conflict (an ipse dixit fallacy). We have to seek out an expert who can speak with authority on the subject. Who is that expert? The heirs to the Apostles, the Pope and bishops in communion with him. Catholics believe that as successors to the Apostles, they share in the authority Our Lord gave His disciples. So, if an individual's interpretation of Scripture or a Church teaching does not match what the magisterium today teaches, then we know the individual does not speak the truth.
Once we realize that, we will recognize them as false teachers. Even if they are sincere, they do not speak the truth about what the Church teaches and what they claim against her cannot be trusted.