This book is indispensable for a modern Christian, often living in difficult conditions, when his faith is daily attacked by unbelieving relatives and friends. And doubts and all sorts of questions often arise in his own soul. He wonders how to resolve the contradiction between the temptations offered in abundance by the modern world and the Orthodox faith, what of the achievements of progress is permissible for Christians to use, and what we must refuse so as not to betray our faith. This book, collected from the opinions of the Holy Fathers on various issues, is intended to help understand all this. It will also help an unchurched person to find out what Orthodoxy is and solve many pressing issues.