Before the Narrow Door is not just another evangelistic book. The author sought to give it a very specific focus, directing it not to "millions of people [...] far from God and peace," but "to a smaller group that is not far from the Kingdom of God." This book is for people who feel all kinds of impediments (internal and external) to entering through the "narrow door" that the Gospel speaks of.
The author wrote in the preface to this work: "I have prepared this small book with the fervent hope that He will use it for the blessed purpose of leading those who seek Him to an immediate and simple trust in the Lord Jesus."