Objective truth is something that is really true, it corresponds with reality, and can in principle be verified by others. Subjective truth, on the other hand, may be true for you but not for me, and cannot be verified by another. “Dogs have four legs” is an objective truth, but “I like dogs” is subjective.
Christians (generally) believe that their beliefs in God are objectively true, whereas unbelievers sometimes claim that they are only subjective. Recently the Wintery Knight blog (William Lane Craig asks: are there objective truths about God?) summarised a talk by philosopher William Lane Craig on some of the arguments about objective truth. It may be a bit obscure for some, but I found these two arguments interesting.
Some people (sometimes labelled as ’empiricists’) argue that only statements that can be verified by our senses can have any objective meaning. It is said that religious claims cannot be verified using our senses (e.g. we cannot see or measure God), and therefore statements about God are objectively meaningless.
But Craig suggests we consider the basis of verificationism, that “Only propositions that can be verified with the 5 senses are meaningful”. That statement cannot be verified with our senses, so it must be meaningless, which makes the statement self-refuting.
Objection #2: Mystical Anti-Realism
It is sometimes argued that claims about God are neither true nor false, they simply reflect how the person feels. But again we can see that this statement is about God and claims to be true, contrary to what it says. Again, the statement is self-refuting.
The moral of the story
It is not uncommon for postmodern thinkers to make statements sceptical of our ability to know anything, especially about God. But often these statements are self-contradictory. If we are going to be sceptical, we must equally be sceptical about scepticism. The most such a sceptic can logically claim is a form of agnosticism – that we cannot be certain about anything, including what we cannot be certain about. Strong atheism is often self-contradictory.
Christians have every right to believe for reasons that are not totally verified by our senses, although I believe that there is also strong objective evidence for christian belief (see Why believe?).
I have written more on how we know (called ‘epistemology’) in Truth and evidence.