How can any one religion be correct when each claims to be correct?
I respect your question, but I don’t think you need my help to answer it. Suppose you were an astronomy student. How would you answer if someone asked, “How could one theory of planetary formation be correct, when each claims to be correct?” Or, since you are in law school, how you would answer if someone asked, “How could one explanation of legislative intent be correct, when each claims to be correct?”
Disagreement does not invalidate the quest for the truth; it is the reason for the quest for the truth. The fact that different answers are in competition with each other does not suggest that there is no answer, but that to find it we must seek it.
The most important prerequisite for the search – and the one most often overlooked – is really wanting to find what you are looking for. Do you want to?