Hegumen Mark (Lozinski). "Patericon of the preacher".
A novice got rid of the thoughts of blasphemy and disbelief only after a confession to the elder.
The former abbot of the Holy Trinity-St. Sergius Lavra, archimandrite Kronid, has told about himself the following: "In the Lavra, I was taken under the spiritual guidance of the elder, father Nicodemus, a man simple in heart but wise in his soul, very kind, and I made friends with him spiritually. Such a life, apparently, was not much liked by the enemy of our salvation. He attacked me with such a terrible rage, he confused me with thoughts of blasphemy against God and unbelief that my mind was almost clouded. Then the Lent of 1878 began. In the Clean Monday I went to matins in the refectory church, rejoicing that the Lord has vouchsafed me to live on till these great days and to fast in repentance. Here I fixed my gaze on the local icon of the Savior in the prayer to Him for help in the salvation. Suddenly, a thought of unbelief and blasphemy against Christ the Savior as a lightning flashed in my mind. That made me so scared that I was like deadened. At the same time I felt like a spark of the hellfire ran all over my body, and my heart was filled with deadly boredom. Then, fearing and trembling, I turned my gaze to the icon of the Mother of God, praying to protect me from the terrible and pernicious thoughts. But to my horror, I noticed that the thoughts of blasphemy against God and against the Mother of God rose in me even stronger. Then I turned to Saint Sergius in the prayer. But a bad mental abuse with terrible power fell upon him too. Then the words of abuse, unbelief and blasphemy poured out in my mind in an irresistible flow on all holy and, terrible to say, even on the Holy of Holies, that is, the Holy Mysteries. Because of excruciating anguish I deadened and went out of my mind with worry. My emotional torment was so great that my face changed completely in five days. Archimandrite Leonid once drew attention to me and asked, "Constantine! What’s wrong with you? I do not recognize you!” I answered him that I was feeling unwell. Friday came, but the thoughts still continued. I was going to confess to my spiritual father, and the thoughts told me: "Will you really tell your confessor all harmful, blasphemous thoughts?" I took the mental advice and said nothing about the thoughts at the confession. But coming out from the cell of the confessor I felt such heavy anguish that I could not restrain my sobs because of the terrible inner commotion and crying like a child I fell on the sofa which stood near the door. The confessor was confused and asked me: "Kostya, what's wrong?" I told him: "Father! I am ruined! "-" How can you be ruined? "Then I told him my mental thoughts tormenting me all week from the Clean Monday. Listening to me, the spiritual father asked, "Do you console yourself with these thoughts?" I told him: "I do not console myself, farther, but I suffer indescribably." Then the confessor led me to the cross and the Gospel again, read the prayer of absolution anew and dismissed me. After that, my heart was so easy that I did not go from the confessor but flew on wings of joy. All scary thoughts vanished, and I, a sinner, could proceed calmly to the Holy Chalice. " (Trinity monastery letters from the spiritual meadow. P. 43.)