After much thought, however, I have come to realize that my answer to the same question is a resounding Yes! For example, I think if God told me that I need to move to another city, I could probably take that on faith. And that's if I'm pretty sure that it was indeed God telling me. If I felt that God Himself wanted me to drop out of school right now and join the Peace Corps, it would be pretty hard, but I would exercise faith in doing so.
But let's use a biblical example and say that I felt just as strongly as Abraham that God wanted me to sacrifice my young daughter to Him. I would probably pause a moment or two to rethink that prompting. Then even if God spoke to me face to face and commanded me to kill my daughter, I think it would be time to check myself into an institution for the mentally ill.
Now, Abraham was a god-fearing man, no doubt. He felt that he was doing God's will. But so does every suicide bomber (more). So did the crusaders (more). So did Jim Jones' followers (more). So did Adolf Hitler (more). Think how the world might be different right now if these people had paused for a moment and asked, "Is this really what I should be doing? Am I following the Creator of the universe, or the voices in my own head? Or am I following the leaders, but not necessarily God?" Too often, people assume that an impulse or feeling is indicative of God's will.
Now let's look at the other side; how can we establish that something is not of God? On my mission in Germany we often asked people a question after introducing the Book of Mormon; "If this book comes from God, wouldn't that be important to know?" I think that is an excellent question. If one does believe in God, it should be very important to evaluate a claim that He has spoken. I would not consider it a healthy reaction to immediately discredit such a claim - because it might be true. Similarly, if I passed a man on the street who said he was Jesus Christ, I would of course be skeptical. But I'd listen to what he had to say - what if it were true? That would be important to know. But as I would probe to evaluate his claim, at what point would I decide he wasn't really Christ? Would I wait until his grammar slipped up; until he was unable to answer some questions about the Bible; until he asked for my credit card number; until he told me to burn down my own house?
Perhaps there is a fine balance between faith and skepticism in order to lead a healthy and spiritual life. We shouldn't accept every claim we hear, but we shouldn't discount them all either. One makes us endlessly gullible, the other leaves us numb and without hope. Each claim must be evaluated from a position of knowledge and faith. One should obtain as much knowledge as possible, and faith can do the rest. Faith should not be used to discount what we can and do know.