Chesterton uses an outline of the history of Western civilization to explain why the Christian world view is credible. C. S. Lewis credited this book with bringing him to Christ. If you're considering Christianity but have intellectual objections, or if you're a Christian wondering how to explain your faith to inquiring friends, you must read this book.
Chesterton himself was a Roman Catholic, but this book lies squarely in the mainstream of the Christian faith, as shared by Catholics, Protestants, Orthodox, Evangelicals, and Pentecostals. For more on this common body of belief, read Lewis' book, Mere Christianity