In the 12th chapter of Matthew is an interesting confrontation between the Pharisees and Jesus. He had been healing people and delivering them from the devil. Bystanders were so amazed that they wondered if he was the Messiah. However, there were Pharisees that also observed the incident. They accused Jesus of doing this work by the power of Satan and not by the power of God. He challenged them by saying it was totally ridiculous that Satan would cast out Satan.
Jesus went on to say that every sin and blasphemy can be forgiven except one. That sin was speaking against the Holy Spirit. Jesus said that the sin would remain with the person in this life and even in eternity. But what is this speaking against the Holy Spirit? The Pharisees never mentioned the Holy Spirit. They challenge Jesus. How is it that the conversation went from their challenge to the unforgivable sin? Was Jesus simply making a comparison? Perhaps this was built into the conversation for some implication that their challenge included the Holy Spirit.
Jesus also made the comment that whoever was not with him was against him. He stated that those in his opposition were not gatherers but those who scattered. What were they scattering?
Certainly, the goodwill of Jesus and his miraculous works were apparent. No doubt the power of Christ was preeminent. What was it that caused these Pharisees to be in such great opposition? A panoramic view of the situation will help answer the question. These were the religious leaders who had respect, power, and high position. Their standing in the religious world was being threatened. Because of the hardness of their hearts they had no intention to support Jesus. Perhaps that hardness that now seems so obvious is why Jesus brought up the Holy Spirit. This opportunity to receive Christ as Savior was being scattered by the Pharisees.
Ephesians 2:8 tells us that saving faith is a gift of God. The reason it is a gift of God is that salvation is not through works but by faith. It is this submission by mankind to God wherein he works within our hearts for salvation and that is demonstrated by our walk.
In other words, we cannot just arbitrarily say that we have faith and are saved. There must be a connection with God to receive a gift that enables faith to go beyond human ability. The eighth chapter of Romans gives us a profound explanation of the relationship between the believer and the Holy Spirit. It describes the walk of belief, the desire of the believers towards spiritual things, and that the Holy Spirit dwells within the believer It also says that those that are led by the Spirit of God are the sons of God. Going further the text says that the Holy Spirit gives witness within the heart of the believer that he is the child of God and joint heirs with Christ.
In so many places throughout the New Testament statements are made that we live by faith, that our hearts are purified by faith, are sanctified by faith, are comforted by faith, gain the righteousness of God by faith, and are justified by faith. Therefore, without faith there is nothing to relate to God. And from where does that faith come? As stated above in Ephesians that faith is a gift of God.
By the Pharisees witnessing the miracles of Jesus and attributing them through works of the devil they also were blasphemy against the Holy Spirit. They were resisting the witness of the Holy Spirit. They refused to let faith by the Holy Spirit to come into their hearts.
We can only say that the unforgivable sin is resisting the work of the Holy Spirit. This work begins with salvation and the gift of faith. Without these a person cannot be saved. As such the person is condemning himself to an eternal damnation. This is strongly supported by John 3:18 that says whoever does not believe has condemned himself.
Whoever is open to the work of the Holy Spirit in their heart will receive the gift of faith and enjoy the grace of God to righteousness and eternal life. Whoever rejects the opportunity of experiencing the Holy Spirit as he leads from the state of being lost to the state of being saved, causes himself to be in a perpetual state of unsaved and that is the unforgivable sin. Is that one last moment that the unbeliever says he will never accept Christ.
In short, to reject Jesus Christ as Savior (who would lead to salvation by the working of the Holy Spirit) has condemned himself. To reject salvation is to condemn to death eternally