Greg Boyd is a theologian and an open theist. This book is about the real correspondence that took place over a couple of years between his unbelieving father and him. If you don't like Open Theism, you will find some stuff you like and some stuff you definitely won't like at all. If you do, or can stand it, this book offers pretty good material when it comes to all the questions about God and the Christian faith that unbelievers might have. A quote:

all the creatures which God creates to share love with must go through a "probation period"-a period in which they choose to love or not love. They could not just be created "in heaven." Once chosen, however, for whatever period of time is necessary (depending on their nature), they become solidified in their decision. That is what the Bible means by heaven and hell. It is the "externalization" of one's character. (p 52)
My question still remains, but Christ has won my trust in Him by showing me His beauty - the beauty of a love, a grace, a tenderness, a gentle strength which no mere human being could ever match. He won my love and trust through the healing compassion of His eyes and the warm understanding of His embrace. He provided an understanding in the heart which the mind could never grasp. (That's why the Bible says that God gives believers a "peace that passes all understanding.") (p 75)
No matter what people believe, Dad, their belief will go beyond what the evidence requires them to believe. That's why it's a belief, and not certainty. This is true whether a person believes Christianity is true, or whether he believes Christianity is false. On an intellectual level, both positions involve some degree of risk. One simply cannot have the kind of certainty one has in mathematics about either position. The question is not which belief is strictly required by the evidence, but which belief has the best evidence to support it. (p 225)