Apologetics, the science of the principles that set forth the truths of Christianity. The book of Archpriest V. Zenkovsky on the website of the Holy Trinity Orthodox School is offered to students as a textbook. Vasily Vasilyevich Zenkovsky (1881-1962), Russian Orthodox theologian, philosopher, teacher; priest (since 1942). Since 1919 in exile, since 1926 professor in Paris. This book is devoted to apologetics, i.e. defending Christian teaching, the Christian faith and the Church from those attacks that over the last decade have become particularly persistent and even fierce. It must be admitted that Christianity is now under siege from different sides; those who have not lost faith in Christ the Savior, and those who seek the truth and want to live in truth, must therefore not only know and understand the Christian doctrine, but also be able to defend it from attacks and accusations, from unfair criticism. He who believes in the teaching and work of Christ as the truth has nothing to fear from these attacks; but according to the word ap. Peter (I Epistle, Chapter III, Art. 15) we must be “always ready to give an answer to everyone who asks us to give a reason for the hope that is in us.”