Eternal sin
In Catholic teaching there are six sins that blaspheme against the Holy Spirit. They are: Several passages in the Bible are frequently interpreted as referring to the unforgivable sin:
Robert Thieme
Thieme believed contemporary Christianity has superimposed a number of false actions on the Gospel message. Consequently, at least every Sunday, he would emphasize what did not need to be done for salvation: 
Thieme held that these actions, while some of them might be commendable from the human viewpoint, are an intrusion on faith. Faith is the absence of merit, and no human good of any form is acceptable to God for salvation. God extends the invitation to salvation, not the other way around. The Greek verb "metanoeo", translated "repent" in the Bible, when used in connection with salvation, means to change one's mind about Christ and believe in him at the point of Gospel hearing. At that point, the grace of God does everything necessary to make faith effectual for salvation. The only personal sin that results in eternal condemnation is to die without having personally believed in Jesus Christ as Savior. God solved the sin problem, and made an issue of individual volition. God knows the thoughts of every individual, and is not constrained by geographical isolation or linguistic barrier in his dissemination of the salvation message to those who desire a relationship with him. Water baptism and legitimate church activities are post-salvation functions of the believer, not prerequisites for salvation. 
Thieme categorized the Christian's life into three phases: the moment of salvation, the post-salvation life of the believer on Earth, and the believer in eternity. These distinctions allow the proper interpretation of verses pertaining to salvation (e.g. Acts 16:31, Eph. 2:8-9, Gen. 15:6), and verses pertaining to the post-salvation function of the believer (e.g. Jas. 2:17), so as not to obscure the simplicity of faith alone in Christ alone for salvation.