G. K. Chesterton 
Orthodoxy [PDF ebook] 

In Orthodoxy, a classic work of Christian apologetics, G. K. Chesterton writes with the purpose of attempting "an explanation, not of whether the Christian Faith can be believed, but of how he personally has come to believe it." Christianity, in Chesterton’s original view, is the "answer to a riddle" and the natural solution to our needs, and in this way it is deeply personal rather than an arbitrary truth from outside one’s experience. Orthodoxy is the culmination of Chesterton’s free-thinking and well-reasoned inquiry as he seeks an explanation to the mystery of being human.