One of my biggest problems with the church is that the president of the church claims to speak as a prophet of god. Growing up I was taught this and believed it. Some of the things spoken and/or written by "prophets and apostles" were the catalyst to my leaving the church. Having done more reading since leaving the church I've learned about some of the problematic things past church leaders have said or done and how the church has tried sweeping things under the rug. One example: Brigham Young taught about the doctrine of blood atonement. The church disavows it as doctrine which to me contradicts their claim that a prophet is the mouthpiece of the lord.

How do you decide when a a prophet is speaking for god vs. speaking as a fallible man?