If someone else had access to the essentially the same claimed experiences how would you respond?
The belief is that the Holy Spirit will not lie and will tell the same truth to everyone. So I would need to know specifically what was claimed, what knowledge was received, and if there actually is a contradiction.
If the person claims to have contradictory experiences to me yet everything else still matches then I would ask if their experience is reproducible. That is, my claim is that there is a specific procedure to receive revelation so I would want to know what theirs was. If there is none then I would be willing to dismiss the claim as someone that was aware of my faith attempting to deceive me. If there was one and it involved morally objectionable actions then I would chalk up the claim to a different entity, if the claim involved mind altering drugs I would chalk it up to the drugs.
If the procedure did not involve something morally objectionable then I would be willing to test it out. If an apparently contradictory answer was received I would then attempt to receive further revelation from both sources, specifically asking what was happening. In particular I would attempt to find some specific life action that is different between the sources of revelation and then see what the effects of following or not following that action are in other people. If either is obviously bad then I would know which one I don't want to follow. If there is no obvious ill effect to either then I would ask each which one I should follow and see if there was a consensus. If both forms do agree as to which I should follow then that is the one I would follow and I would hope that an explanation could be had on the other source.
If there is no agreement and no way for me to determine if either is lying then I would go see a doctor to see if something is off with me. If there is and some method of fixing the problem is given I would then repeat both procedure to see which still responds. If they both still respond or if I am determined to be fine then I would decide at that point what to do, either continue following the one I have been and hope for the best or become a deist try not to violate anything of either and hope for the best.
Hopefully that answers the question. I do not anticipate running into anything past the first line of the third paragraph, being testing out the other procedure. Given that I answered poorly by using previous experiences I have tried not to let my own experiences on this subject influence my answer. Generally evangelicals will tell me to read the bible and pray about it, something that is completely consistent with my own beliefs and somewhat confusing given I have read the bible many times and prayed about it many times, I know it to be true.
if the other individual has his own set of contradictory scriptures, how do you decide that your set is better than his set?
First, I would read their scriptures to see what is said. If there is an internal contradiction I would ask for an explanation of said internal contradiction. That is in my experience as far as it has ever gotten, but we are dealing in hypotheticals here so I will continue. If the individual is still willing to talk with me and explain the apparent contradiction I would ask how can I know that their scripture is true. See above for the rest of the response.
(Disclaimer: This post is sympathetic to a certain subset of theists. I am not myself a theist, nor have I ever been one. I do not intend to justify all varieties of theism, nor do I intend to justify much in the way of common theistic behavior.)
I'm not adopted. You all believe me, right? How do you think I came by this information, that you're confident in my statement? The obvious and correct answer is that my parents told me so1. Why do I believe them? Well, they would be in a position to know the answer, and they have been generally honest and sincere in their statements to me. A false belief on the subject could be hazardous to me, if I report inaccurate family history to physicians, and I believe that my parents have my safety in mind. I know of the existence of adopted people; the possibility isn't completely absent from my mind - but I believe quite confidently that I am not among those people, because my parents say otherwise.
Now let's consider another example. I have a friend who plans to name her first daughter Wednesday. Wednesday will also not be adopted, but that isn't the part of the example that is important: Wednesday will grow up in Provo, Utah, in a Mormon family in a Mormon community with Mormon friends, classmates, and neighbors, attending an LDS church every week and reading scripture and participating in church activities. It is overwhelmingly likely that she will believe the doctrines of the LDS church, because not only her parents, but virtually everyone she knows will reinforce these beliefs in her. Given the particular nuances of Mormonism as opposed to other forms of Christianity, Wednesday will also be regularly informed that several of these people are in a position to have special knowledge on the subject via direct prayer-derived evidence2 - in much the same way that her parents will have special knowledge of her non-adopted status via direct experience when she wasn't in a state suitable to notice or remember the events. Also, a false belief on the subject could have all kinds of bad consequences - if the Muslims are right, for instance, no doubt Hell awaits Wednesday and her family - so if she also correctly assumes that her parents have her best interests at heart, she'll assume they would do their best to give her accurate information.
Atheism tends to be treated as an open-and-shut case here and in other intellectually sophisticated venues, but is that fair? What about Wednesday? What would have to happen to her to get her to give up those beliefs? Well, for starters, she'd have to dramatically change her opinion of her family. Her parents care enough about honesty that they are already planning not to deceive her about Santa Claus - should she believe that they're liars? They're both college-educated, clever people, who read a lot and think carefully about (some) things - should she believe that they're fools? They've traveled around the world and have friends like me who are, vocally, non-Mormons and even non-Christians - should she believe that her parents have not been exposed to other ideas?
Would giving up her religion help Wednesday win? I don't think her family would outright reject her for it, but it would definitely strain those valued relationships, and some of the aforementioned friends, classmates, and neighbors would certainly react badly. It doesn't seem that it would make her any richer, happier, more successful - especially if she carries on living in Utah3. (I reject out of hand the idea that she should deconvert in the closet and systematically lie to everyone she knows.) It would make her right. And that would be all it would do - if she were lucky.
Is it really essential that, as a community, we exclude or dismiss or reflexively criticize theists who are good at partitioning, who like and are good at rational reasoning in every other sphere - and who just have higher priorities than being right? I have priorities that I'd probably put ahead of being right, too; I'm just not in a position where I really have to choose between "keeping my friends and being right", "feeling at home and being right", "eating this week and being right". That's my luck, not my cleverness, at work.
When Wednesday has been born and has learned to read, it would be nice if there were a place for her here.
1I have other evidence - I have inherited some physical characteristics from my parents and have seen my birth certificate - but the point is that this is something I would take their word for even if I didn't take after them very strongly and had never seen the documentation.
2Mormons believe in direct revelation, and they also believe that priesthood authorities are entitled to receive revelations for those over whom they have said authority (e.g. fathers for their children, husbands for their wives, etc.).
3I have lived in Salt Lake City, and during this time was, as always, openly an atheist. Everyone was tolerant of me, but I do not think it improved my situation in any way.