The book takes the reader to the roots of the Christian faith in order to answer the questions posed in the title: what do Christians believe, why do they believe it, and why does it really matter?

The book presents a global picture of how, over two millennia of human history, the Orthodox Christian faith has been the greatest driving force in the formation of Western civilization. The flourishing of the faith has brought the countries of the Old and New Worlds a dominant role on the planet, and its neglect today leads to the terrible consequences of cultural collapse, the clash of civilizations, and other problems.

The author touches on the main dogmas (assertions) shared by Christians of all denominations, and tries to prove, using many testimonies and real-life examples – from ancient history to the present day – why believers should hold fast to Orthodox Christianity – the faith handed down once and for all by the saints.