If you are under the impression that a person cannot be both a Christian and a skeptic, you need to rethink your position. The truth is that most Christians are skeptics, albeit of a different kind than people typically associate with that word.
Christians are skeptical of human nature. The reason? Scripture affirms what our experience tells us. Namely, everyone is a sinner and is capable of disappointing us. And in some cases, even deceiving us.
That's not to say that Christians, by their new nature, are suspicious people. That just isn't the case with most believers. What we do find in most Christians is an utter amazement at man's willingness to place so much confidence in his own opinions, feelings and hunches. Christians as a whole tend to place less stock in those unreliable and subjective assumptions. It has to do with Christians being grounded in God's Word and His description of human nature.