The proposed collection of works by the remarkable Russian publicist and theologian M.A. Novoselova (1864-1928) is dedicated to the problems of different understandings of our salvation and redemption by the Lord Jesus Christ, existing in the Orthodox Church, among Catholics and Protestants. Based on Tradition and dogmas of the Orthodox Church, M.A. Novoselov explains the essence of these disagreements and reveals the fatal error of the Western Churches in matters of dogma. The author does not ignore the key aspects of Eastern and Western Christian mysticism, which had a huge impact on the different understanding of holiness and salvation in Orthodoxy, Catholicism and Protestantism. The book is compiled from separate issues of the “Religious and Philosophical Library”, published in 39 issues and published by M. A Novoselov from 1902 to 1917. The book is intended for everyone who is interested in the foundations of Orthodoxy, dogmatics and mysticism of the Orthodox Church.