Christian Apologetics is based on the existence of truth, and Christianity’s correspondence to reality. This article from the Baker Encyclopedia of Apologetics will help you better understand what truth is.
This is part three of three.
The Absolute Nature of Truth. The relativity of truth is commonly a premise of current thought. Yet orthodox Christianity is predicated on the position that truth is absolute. Thus, the defense of the possibility of absolute truth is crucial to the defense of the historic Christian faith. According to theories of relative truth, something may be true for one person, but not for all people. Or, it may be true at one time, but not at another. According to the absolutist view, what is true for one person is true for all persons, times, and places.
As argued above, there is only one adequate view of the nature of truth—the correspondence view. Other views, such as coherence and pragmatism, describe tests for truth, not an explanation of the nature of truth itself. Factual truth is that which corresponds to the facts. It is that which corresponds to the actual state of affairs being described.
Relative Truth. The relativity of truth is a popular contemporary view. However, truth is not determined by majority vote. Let’s take a look at the reasons people give for belief that truth is relative.
Of all, some things appear only to be true at some times and not at others. For example, many people once believed the world to be flat. Now we know that truth statement was wrong. It would seem that this truth has changed with the times. Or has it? Did the truth change, or did beliefs about what is true change? Well, certainly the world did not change from a box to a sphere. What changed in this regard is our belief, not our earth. It changed from a false belief to a true one.
Within a statement’s universe of discourse, every truth is an absolute truth. Some statements really apply only to some people, but the truth of those statements is just as absolute for all people everywhere at all times as a statement that applies to all people generally. “Daily injections of insulin are essential for continued life” is true of persons with some life-threatening forms of diabetes. This statement has an applied universe of discourse. It isn’t purporting to be a truth that applies to everyone. But if it applies to Fred, then it is true of Fred for everyone. The caveat that this statement is false for people with a normally functioning pancreas does not detract from the statement’s truth within its universe of discourse—diabetics to whom it is properly addressed.
Some statements appear to be true only for some. The statement, “I feel warm” may be true for me but not for another person, who may feel cold. I am the only one within the statement’s universe of discourse. The statement, “I [Norman Geisler] feel warm” (on July 1, 1998, at 3:37 p.m.) is true for everyone everywhere that Norman Geisler did feel warm at that moment in history. It corresponds to facts and so is an absolute truth.
A teacher facing a class says: “The door to this room is on my right.” But it is on the left for the students. Relativists argue that surely this truth is relative to the teacher since it is false for the class. But on the contrary it is equally true for everyone that the door is on the professor’s right. This is an absolute truth. It will never be true for anyone, anywhere at any time that the door was on the professor’s left during this class on this day in this room. The truth is equally absolute that the door was on the student’s left.
It seems obvious that the temperature frequently is relatively high in Arizona and relatively cold at the North Pole. So, apparently some things are true for some places but not for other places. Right?
Not so. Some things are true concerning some places, but not true in other places where the conditions are different. But that isn’t the point. Within the Arizona weather report’s universe of discourse, the statement corresponds to the facts. So it is true everywhere. The statement: “It is relatively cold for earth at the North Pole” is true for people in Arizona in the summer, or on Pluto where it is colder than on the North Pole. Truth is what corresponds to the facts, and the fact is that it feels cold at the North Pole.
All truth is absolute. There are no relative truths. For if something is really true, then it is really true for everyone everywhere, and for all time. The truth statement 7 + 3 = 10 is not just true for mathematics majors, nor is it true only in a mathematics classroom. It is true for everyone everywhere.
Geisler, N. L. (1999). In Baker encyclopedia of Christian apologetics (pp. 741–743). Grand Rapids, MI: Baker Books.