Many Christians believe that they have to understand everything about their faith for that faith to be genuine. This isn't true.
There are many things we don't understand about God, His Word, and His works. And this is actually one of the greatest things about the Christian faith: that there are areas of mystery that lie beyond the keenest scholarship or even the most profound spiritual exercises. Sadly, for many people these problems raise so many questions and uncertainties that faith itself becomes a struggle.
But questions, and even doubts, are part of faith.
Chris Wright encourages us to face the limitations of our understanding and to acknowledge the pain and grief they can often cause. In The God I Don't Understand, he focuses on four of the most mysterious subjects in the Bible and reflects upon why it's important to ask questions without having to provide the answer:

1. The problem of evil and suffering.
2. The genocide of the Canaanites.
3. The cross and the crucifixion.
4. The end of the world. 

 
"However strongly we believe in divine revelation, we must acknowledge both that God has not revealed everything and that much of what he has revealed is not plain. It is because Dr. Wright confronts biblical problems with a combination of honesty and humility that I warmly commend this book." —John Stott