What constitutes the sin against the Holy Spirit?

Brother P, you ask if you have committed the sin which has no forgiveness in this life or in the life to come. I answer: I do not see the slightest evidence that this is the case. What constitutes the sin against the Holy Ghost? It is willfully attributing to Satan the work of the Holy Spirit. For example, suppose that one is a witness of the special work of the Spirit of God. He has convincing evidence that the work is in harmony with the Scriptures, and the Spirit witnesses with his spirit that it is of God. Afterward, however, he falls under temptation; pride, self-sufficiency, or some other evil trait, controls him; and rejecting all the evidence of its divine character, he declares that that which he had before acknowledged to be the power of the Holy Spirit was the power of Satan. It is through the medium of His Spirit that God works upon the human heart; and when men willfully reject the Spirit and declare it to be from Satan, they cutoff the channel by which God can communicate with them. By denying the evidence which God has been pleased to give them, they shut out the light which had been shining in their hearts, and as the result they are left in darkness. Thus the words of Christ are verified: “If therefore the light that is in thee be darkness, how great is that darkness!” For a time, persons who have committed this sin may appear to be children of God; but when circumstances arise to develop character and show what manner of spirit they are of, it will be found that they are on the enemy’s ground, standing under his black banner.    Testimonies for the Church, Vol. 5 p. 634

 

In this, our day, men have placed themselves where they are wholly unable to fulfill the conditions of repentance and confession, therefore they cannot find mercy and pardon. The sin of blasphemy against the Holy Spirit does not lie in any sudden word or deed—it is the firm, determined resistance of truth and evidence. MS 30, 1890, par. 16