Faith gives us objective knowledge. Opinion, by definition, is subjective.
Opinion may, in fact, turn out to be objectively true, but that is not what is being asserted when one says "It is my opinion that … ". Such a statement asserts that the person holds some degree of probability that the object of his opinion is true, though without certainty.
In our culture where objective truth is called into question, philosophically, there is the constant temptation to phrase everything as "It is my opinion that … " rather than to say “It is the case that …” This is the result of philosophical skepticism, which implies that there is no real certainty to our knowledge; hence, everything becomes subjective opinion.
There are two modes of acquiring knowledge: faith and reason. Reason, of course, uses observation and the rules of logic to discover truth. Faith, which can be either natural faith or supernatural faith, accepts as true what someone tells us. We first put our faith in some person, usually because of some authority that he demonstrates, and secondly we accept as true what that person says.
We use our own reason to discover truth every day. But most of what we actually know, as individual persons, comes to us through natural faith. That is, we believe our parents, our teachers, our professors, the books we read, because of their authority. No one alive today has seen George Washington or knows firsthand that he was the first president, but we believe it on natural faith because there is so much evidence: which means, there is so much testimony. We believe it because someone said it was true, and we trust them. Or, at the least, we conclude that it is true, using our own reason, because of the many reliable witnesses.
With supernatural faith, we also have access to objective truth, just as we do through natural faith, except that supernatural faith gives us even more certainty–because the authority in whom we put our trust is God, who can neither deceive nor be deceived.
And so, when we say “I believe…” in the context of supernatural faith, we are not saying “It is my opinion that …”. Rather, we are asserting that the object of our belief is objectively true. To say “It is my opinion that God exists” is to reduce the proposition to subjective opinion, and hence it implies that there is no objective certainty. I would think that this is equivalent to saying, “I like chocolate.” This is, indeed, subjectivism.
One could say, though, “It is my opinion that it is true that God exists”, which is a little more complicated to analyze. I think that this would imply that you do believe that the proposition is objectively true, only that you do not want to force this conclusion on someone who has not had the same opportunity to come to faith as you have. Rather, it would respect the process of coming to faith, while at the same time asserting that what you believe isn’t merely subjective, but is objectively true. I hope this makes sense. I agree that it is important to be diplomatic and charitable when speaking with unbelievers, but it is also important to be precise in our language.
Yes, other people may have other beliefs, but if we believe that God exists, for example, then someone who “believes” that God does not exist is, objectively speaking, in the wrong. We are called to respect the person who has the belief, though not necessarily the belief itself (this is what I believe that John Paul II was doing when he kissed the Koran, for example: he wasn’t implying that the Koran and Islam are true, but rather, he was showing respect for the people who hold their sincerely held beliefs).
Anyway, in any given situation, I would pray to the Holy Spirit to find the right words. I might say, “I believe that God exists. I think it is true. I respect that you do not believe it, but I hope that you would consider the following evidence and arguments in favor of God’s existence…etc.”
I don’t know if any of this helps, or if I simply muddled the water! God bless…
