The question that’s made the biggest difference in my life is “Why?” And why is that, you ask?
It applies everywhere and at all times!
E.g., Why do I believe in God? Why do I follow the New Testament? Why am I alive? Why am I living in Illinois right now? Why am I preaching? Why am I on the computer when I’ve got some other things to tend to?…
[my wife keeps asking this one: Why hasn’t this baby been born yet? :)]