How do I deal with doubt?

Question from Evan:

Hi Pastor Bob, my name is Evan. ...I've been to your church a few times before and you are an awesome pastor! I've got a question to ask you concerning doubt-

I've been experiencing an incredibly close relationship with Christ, salted by sufferings and everything. I've even felt an very deep calling to be a missionary for the rest of my life. But recently i've been experiencing a huge amount of unbelief and doubt. I'm not sure where it came from- or what it concerns, because it doesn't seem to come from any specific objection to Christianity- it's almost as if my heart totally believes in Christianity, but my mind won't accept it. (as of the past few weeks) It may possibly be the other way around- I'm not totally sure. Just wanted to ask you though- how would you recommend dealing with doubt on such a large scale? I've experienced some small bouts of it, but never so heavy as the doubt I feel now. Thank you!

Answer from Pastor Bob:

Evan, thanks for writing.
Doubt is a normal thing. Great men of God like Elijah had their doubts (right after his triumph in 1 Kings 18, he fled and doubted God in 1 Kings 19).
Here's a great prayer to pray when you have doubts. When a man doubted Jesus, he said, "I do believe! Help my unbelief." (Mark 9:24). If you think that's not a prayer, read Mark 9:29 and you will see that Jesus called it a prayer.
Let me recommend a book to you: The Reason for God by Timothy Keller. Keller is a Presbyterian pastor in Manhattan who has successfully grown his church to 6,000 people in the middle of a liberal city full of skeptics. His book is based on numerous conversations with intellectuals and doubters in New York City. He stands by his faith, but does so in a winsome and attractive way. His reasons are solid and believable.
I would also recommend to you The Apologetics Study Bible. It has comments throughout the Bible anywhere that skeptics doubt things or false religions have twisted things, and gives a good, reasonable explanation for difficult Bible passages, plus lots of articles defending the faith.