I was asked to share my thoughts on this question today, though as you can probably guess I’ve heard this one before.
People often leap to the task of answering a question like this without first taking a breath and examining the question itself. But what does it even mean to ask if Christianity is the only true religion?
True as in making true theological claims?
Does it commit one to saying that Christianity is the only religion that makes true claims about God and how to relate to him? Because that can’t be true since many religions make the same claims about God as Christianity. So if the Christian believes those claims are true when a Christian confesses them, they must believe those claims are true when the non-Christian confesses them. Consider for example:
“How many gods are there?”
“Is God the creator of all?
And so on.
True as in making the most important true theological claims?
Could it be that “only true religion” means “the only religion with the most important truths”? This too is a non-starter since I take it Christians will agree that “There is one God” and “God is creator of all” are not mere truths, but are among the most important theological truths.
True as in successfully referring to God?
Perhaps “the only true religion” can be taken as affirming that only Christians make true claims about God because all non-Christians suffer reference failure. Could it be that only Christians succeed in referring to God when they use the term “God”?
There are two main theories of reference. The first is a descriptivist theory according to which reference succeeds only if the person has a sufficient number of correct descriptions of the entity in mind when they use the term. Thus, for example, only the Christian would have “God is triune” and “God the Son incarnated as Jesus” in mind. Perhaps then this is what is meant: Christianity is the only religion where its practitioners have the set of true descriptions that allow them to refer successfully to God.
There are two problems here. The first is with the descriptivist theory of reference itself which is an issue beyond the scope of this discussion. The second is that it is by no means clear that non-Christians do not grasp sufficient content about the concept of “God” to refer to God. For example, many non-Christians believe in one necessarily existent, omnipotent, omniscient and omnipresent creator and sustainer of all things. That descriptor would seem sufficient to establish reference.
The second theory of reference is causal-historical. It begins by an individual “baptizing” a referring term for a particular use and later people simply adopting that usage. For example, Abraham says “I believe that God called me out of Ur” and later people say “I believe in the God Abraham believed in.” Could this be what is meant?
However, it is enormously implausible to suggest that Jews (and Muslims, and every other non-Christian) fail to refer to God. While Christians may have been drawn into the causal-history that enables successful reference of God, surely it is implausible to think Jews were altogether grafted out of it. And why can’t any non-Christian say “I’m referring to the God Christians believe in”, thereby referring by joining in the causal-historical processes that enable Christians to refer to God? In addition, while a causal-history may be sufficient to establish reference to God, it is doubtful that it is necessary. Consider, for example, Paul’s exchange on Mars Hill (Acts 17) or his teaching on general revelation (Romans 1-2).
True as in the only means of salvation?
One suspects that this may well be what is really meant by the claim. Christianity is the only means of salvation. But this claim has problems. First of all, it isn’t Christianity that is the means of salvation but rather God in Christ. Second, Christians disagree on whether God in Christ saves people apart from their identity with the Christian community. For example, is an infant in a Buddhist family in China which dies at six months necessarily going to hell? If one believes it is possible that this child is to be saved then identity with the Christian community is not the sole means by which God saves people.
True as in the religion that is closest overall to getting the most important theological claims correct and which is the normative means of God’s salvific action in the world?
Something like this statement, inelegant thought it may be, seems to be the most defensible take on the claim that Christianity is the only true religion. Importantly, a statement qualified in this way — in terms of truth claims and soteriological efficacy — also will mollify significantly much of the initial implausibility that objectors will probably have to the bald claim that only Christianity is “true”.