The question was put:
"I would love to get some of your opinions on a question I've had for a while now. It's in regards to the reliability of the spirit as a source of information/knowledge.
The church teaches a very straight-forward, step-by-step way of obtaining truth and knowledge.
1. Study the particular topic in question.
2. Pray, asking God for an answer.
3. Wait for a response through the Spirit.
Moroni's promise is pretty cut and dry: "by the power of the Holy Ghost ye may know the truth of all things". Over the years, however, it has become apparent to me that this method is fraught with issues that make conclusive results very evasive.
One very difficult question that everyone struggles with on a certain level, if they are being honest with themselves, is how to differentiate between the influence of the spirit and your own thoughts and desires. What would you tell someone who prayed about the Book of Mormon and got an answer that it wasn't true? Would you suggest that their own thoughts were clouding the "correct" answer? How do you know your own thoughts aren't clouding your answer? We are all capable of producing emotions within ourselves with just a thought. How can you be sure that any emotion that you feel and interpret as an "answer" is not simply a product of your own mind? How many times have you felt feelings that you normally associate with the spirit in completely inappropriate places, like during a movie or listening to a secular speech or music? Is that really the spirit you're feeling or are they just emotions that feel like the spirit? If it's the spirit, why would you be feeling it when watching the hero in a movie rescue his girl or some completely non-spiritual act. If it's just plain old emotion kicking in, how can you be sure that when you think you are feeling "the spirit" that it really is the spirit?
In my experience, trying to gain knowledge in this way is very dicey and not nearly as clear-cut as it is made out to be. Moroni promises that you can know the truth of all things through the spirit. If you feel like you have received an answer that the Book of Mormon truly is what it purports to be, do you feel like you could similarly determine the veracity of any document? If someone presented a letter to you that was supposedly written by Joseph Smith, would you be able to pray about it and determine without a doubt whether it was authentic or fraudulent? That test is well within the bounds of Moroni's promise that you can know the "truth of all things" by the power of the Holy Ghost. If you truly can gain knowledge in this manner, why aren't members of the church getting concrete answers to the many questions we have about life in general, e.g., autism, dinosaurs, Bin Laden's location , etc, etc.
Consider this: You sit down with an "investigator", and have intimate discussions about spirituality and talk about how much God loves them and how happy the gospel has made you. You talk about how you "know" the Book of Mormon is true because you've felt overwhelming love from God while you read it, etc. Then the investigator is to read the book, and in a quiet, peaceful place, kneel down and with their eyes closed ask God if this wonderful book is true and wait for the warm, peaceful feeling to sweep over them. Now, I can tell you that with that kind of coaching, even if there is no God, that person is going to generate emotion within themselves or at least feel something that could pass as "a peaceful feeling", especially if they are wanting it.
When you really think about it, relying on emotions to determine truth is very borderline folk magic. Moroni's promise is easily tested. Since the Book of Mormon can't be "proved" true, you would have to test it on something else; if what Moroni says is true, you should be able to test his promise on something other than the Book of Mormon. But no one ever does.
To which I responded:
I truly believe there exists authentic revelation through the Spirit of God. But I also strongly believe that it can often be nearly impossible or impossible to recognize the difference between that an one's own emotions. Therefore, as a general rule, my philosophy is that, in approaching any important question, we should start with knowledge, reason, and the scientific method. When those methods are inadequate to finding an answer (such as to the question of whether God exists), then we should delve into trying to learn the truth through spiritual means, but with an eye towards reconciling our feelings and perceived spiritual experiences with the objective empirical data available to us. Ultimately, even my suggested method is not foolproof, but I believe that, overall, it is much less error-prone than going on "all spirit."