But as Solomon has said, "nothing is new under the sun." For this question, along with the question of God's existence has been with us for centuries and even millennia.
During Pontius Pilate's interrogation, Jesus mentions this word "truth." Pilate's response is much like the question before us today, "What is truth?"(John 18:38). Just like Pilate, many today either believe that truth does or does not exist. Some, including one coworker who I have conversed with will say that we cannot know truth. Others will tell you that we can know some truth, but not the truth about the big things like morality and even God. Both notions oppose the historic view of Truth, also the Christian view, called the correspondence theory of truth. This means a statement is true if it corresponds to a fact in the world. For example, if I said "a monkey is riding a bicycle" is a true statement, it would only be true if and only if the monkey is really riding a bicycle.
The Christian faith claims to describe truth about creation, history and God's plan for humanity. These descriptions presuppose that statements can be true - it is assumed that truth can indeed be known. So how do we respond to people who disagree? I like to ask the person who says truth is knowable, "do believe that statement to be true?"
Now the skeptic might not deny the possibility of all truth, but only those truth claims about religion and God. Or they may answer that truth is relative to people and circumstances or times. They might even go so far as to say that all truth is unknowable. If they want to make this claim, let me give you three roads that you can take to respond to that claim.
First, it is not true that all truth is unknowable. That claim is a self-defeating statement. Why? Because the very statement sets forth a principle that it violates. It would be like saying, "I cannot type a word in English" or "there are not sentences in any book or blog posting that are longer than four words." Of course if you are reading this you would see that I am typing in English and that the last statement is longer than four words. If all truth is unknowable then the declared truth that all truths unknowable is also unknowable as well. The skeptic's challenge has refuted itself.
Second, it can be demonstrated that some truths are known. For instance let's take an anonymous debater. Our anonymous debater's existence can be known because he/she must exist to say that we cannot know truth. In like manner there are geographical and mathematical and historical truths that can be know with certainty. It can be confirmed that 1+1=2 and that Boston, Massachusetts is where the first shots of the American Revolution took place; and that George Washington was the first President of the United States. These facts are known and they are true.
Third, there are many that will deny the knowability of truth only regarding morality and religion. I talk with these folks weekly at the local Community College before and after our Ratio Christi meetings. In a conversation such as this, you and I can ask, "why do you place those subjects in a separate category? How can you justify the inconsistency of divorcing them from truth while keeping math, science, and history in the realm of truth?" Can I be straight up here, many students today do not even know their history mostly because of how it is being taught at the professorial lectern.
Issues about God and spiritual matters either correspond to reality or they do not.. Therefore these two categories are subject to inquiry just like all the other subjects and topics. They can be investigated just as math claims, and historical claims, even if by different methodologies. Many people who say that religion and morality are not knowable are just repeating some trendy phrase that they have heard but not taken the time to think through.
Our culture today is attacking the nature of truth as never before, and as believers you and I should be able to defend the truth. The viability of Christianity stands or falls upon the fundamental concept that truth exists and that truth is knowable. Despite the theoretical nature of our discussions with people who reject the knowability of truth, we should be able to demolish the arguments and every pretension that sets itself up against the knowledge of God, and. . .take every thought captive to make it obedient to Jesus Christ" (2 Corinthians 10:5, paraphrased).
Other Posts From the Real Issue on Truth and Relativism