The Riddle of the Crossroads
You are traveling down a path when suddenly you come upon a crossroads. At the crossroads live two brothers. They are identical in every way except one... one always lies, and the other always tells the truth. The ensuing paths also appear to be identical in every way except for one... one path leads to eternal destruction and the other to eternal life.
You can ask either brother only one question, but upon receiving his answer you will immediately know which path leads to life and can proceed confidently to your destination.
What is the question you ask?