A Pastor is a religious leader in a Protestant church or group. Protestants typically believe in the priesthood of all believers. That means any believer can administer the sacraments and the pastor doesn't need to be ordained specially. Pastors usually need training in Theology but a few groups allow untrained people to become pastors. Minister, preacher and reverend are alternative names for a pastor. [1]
There is a good and a a bad side to Christianity, see the category page