Sherem is not confident that he has fully repented, because he suspects that he has committed the unpardonable sin. This he explains as having said that he believed the scriptures, and yet denying the Christ. Under modern definitions of the unpardonable sin, Sherem would not qualify. Joseph Smith describes the sin as follows:
" All sins shall be forgiven except the sin against the Holy Ghost; for Jesus will save all except the sons of perdition. What must a man do to commit the unpardonable sin? He must receive the Holy Ghost, have the heavens opened unto him, and know God, and then sin against him. After a man has sinned against the Holy Ghost, there is no repentance for him. He has got to say that the sun does not shine while he sees it; he has got to deny Jesus Christ when the heavens have been opened unto him, and to deny the plan of salvation with his eyes open to the truth of it; and from that time he begins to be an enemy. (History of the Church, Deseret Book, 1973. 6:314.)"
Sherem shows no signs of baptism nor of the receipt of the Holy Ghost, and indeed would have denied the efficacy of baptism, since he denied the Christ. Whatever his source of learning of the Law, it did not include the teachings of Nephi and Jacob on the Savior.
Nevertheless, Sherem fears that he has committed this sin. Why? Sherem is a believer in the power of the Law, and the power of one's word or oath. By stating that he believes, Sherem has placed himself in contradiction to the true interpretation of what he said he believed in. By appeal to a more modern understanding of the meaning of the unpardonable sin, we may be more lenient on Sherem than he was on himself. It is instructive, however, that Sherem's confession accepts the responsibility for his actions. He does not blame someone else for teaching him incorrectly, or society for a set of beliefs that misled him. Sherem accepts that he has made a vow of belief, and believed incorrectly - and taught that incorrect belief.
We may also appeal to Sherem's experience with the ministering of angels to suppose that God still thought Sherem's soul as capable of salvation, and that this very public confession was an integral part of Sherem's repentance process.