How do we know that your statement is the truth? Why can't there be as many paths as individuals within the world?
I assume you aimed this at me. I also assume you mean theological pluralism. If correct, you can't know. Faith is not about certainty, it is about the best conclusions. Some of those include:
1. The law of non contradiction. Just among the major faiths you have mutually exclusive claims to absolute truth. Only one can possibly be right.
2. The nature of truth. Truth it's self is an exclusive concept. So any truth claim will reflect that.
3. It is irrational to think a rational God would hide self contradictory, mutually exclusive, and inconsistent paths in mountains of man made garbage dispersed around the world. It is perfectly rational to think he would have one clear, concise, and exclusive method.
4. There is no reasonable correlation between the population and truth.
5. As a principle you do not multiply causes, agencies, or mechanisms beyond necessity.
6. The evidence that accompanies individual claims is vastly unequal. The evidence that accompanies Islam IMO is detrimental not supportive.
7. Logical coherence. Many theological methodologies are incoherent. Hinduism for example just makes no sense. Christian salvation has no flaw what so ever and is perfectly constant. That does not make Christianity true (alone) but it does make other claims false.
That is at least a starting point.