Is one true religion possible? Interesting question. But what if someone truly believes that there is only one true religion....does that make her arrogant?
A common tactic used to silence religious particularists is to claim they are arrogant and immoral for believing that there is only one way to God. In response to this charge, Philosopher Alvin Plantinga asks, “Suppose I think the matter over, consider the objections as carefully as I can, realize that I am finite and furthermore a sinner, certainly no better than those with whom I disagree, and indeed inferior both morally and intellectually to many who do not believe what I do; but suppose it still seems clear to me that the proposition in question is true [e.g., that Jesus Christ is the only way to God]: can I really be behaving immorally in continuing to believe it? It seems not."
Moreover, the charge of arrogance and immorality cuts both ways because implicit in the sophisticated religious pluralist view is the claim that everyone else but them has it wrong! All of the devout adherents of the worlds major religions—billions of people—have it wrong. If that doesn’t count as arrogance, I am not sure what does.
For more on this issue, check out chapter 14 of Welcome to College.