Prophecy is actually the gift of being able to know what God is thinking.
"He who prophesies speaks to men for their upbuilding (oikodome) and encouragement (paraklesis) and consolation (paramuthia; 1 Corinthians 14:3)."
The only reason that a prophet could ever predict anything is because of God's sovereignty. God controls everything, so if you know what God is thinking, then you know what he's going to do.
http://www.joyfulheart.com/scholar/purp-pro.htm Prophets tend to irritate a lot of people because they care a lot more about the truth than they do about other people. That's why so many of them get killed.