Recently I was pointed to this Parade interview with Brad Pitt, in which Pitt describes his departure from Christanity:
"I thought you had to experience things if you want to know right from wrong. I'd go to Christian revivals and be moved by the Holy Spirit, and I'd go to rock concerts and feel the same fervor. Then I'd be told, 'That's the Devil's music! Don't partake in that!' I wanted to experience things religion said not to experience."
Pitt demonstrates the liability of an experience/testimony/personal story as justification for religious belief. Now don't get me wrong. I am not saying experience is an unimportant thing in our justification. I'm just saying it's not the only thing. Unfortunately, I encounter far too many Christians who offer it as the only piece of evidence for their belief in Christ.
But as Pitt reveals, experiences alone can be a poor guide for determining the truth or falsity of our religious beliefs. Everyone's got an experience. The Mormon has one. The Buddhist has one. Even the guy who attends a rock concert has one. Certainly experience alone cannot justify contradictory religious claims. The Christian and the Mormon cannot both be right because they testify to two mutually exclusive views of God. More is needed.
But what is it that adjudicates between the different experiences? That's where different kinds of evidences are needed and why Christians should not rely on their personal testimony alone in the proclamation of the Gospel.