This goes on my must-read list for all unmarried Christians, and on my should-read list for all married Christians. No, seriously: if you're a single/divorced Christian, put this on the top of your list immediately.In his book, Craig Groeschel said, "If you don't know the purpose of something, all you can do is misuse it." Sadly, I see huge numbers of people, many of them Christians, misusing marriage because they don't know its purpose. They not only misuse it once they get married, but they misuse it during their single years by putting their hope in it for eventual self-fulfillment and missing most or all of the incredible and varied blessings marriage provides, most notably character growth.The Kellers do a phenomenal job of explaining God's complete design for marriage* as best we can understand it through the Scriptures and the experience of pastoring a church for many years. And although I am married and look forward to applying some of these principals to my own marriage, I believe the book is most valuable to the unmarried; those hoping to marry one day should know what they are getting themselves into, and those planning never to marry should know what they are missing.I came to this book primarily hoping it would help me teach others a Godly vision for marriage in order to understand the Christian doctrine of premarital abstinence. The book does make a good case for that, but offers so much more as well. The one unfortunate thing is that Keller's writing style is a bit "scholarly" and so may be difficult for Christian teens, who are in need of this book as much as anyone.I expect this will be a book I re-read and reference many times in the future.*This is not merely the accurate but very shallow definition many Christians publicly support: "Marriage is between one man and one woman." That is one small facet of marriage, but offers nothing about its purpose, only its regulation. The book addresses the way the two genders complement and challenge each other, but does not even put a toe into the gay marriage debate; that might likely be a worthy topic for an entirely separate book.