I am concerned that earlier in my life I may have blasphemed of the Holy Spirit. What is that, and is that the unpardonable sin?
First, the passage in question is in three of the four gospels. (Mt. 12:29-32; Mk. 3:29-30; Lk. 11:221-22)
The context is an encounter between Jesus and the Pharisees. Jesus drives out a demon from a man who was blind and mute. The Pharisees accuse Jesus of using the power of Satan to drive out the demon from the man. Jesus casts out the demon by the power of the Spirit. But the Pharisees attribute it to the power of Satan. Thus, they call the Holy Spirit the unholy spirit.
The Pharisees were unable to accept Jesus as the Messiah, so much so that they accused Him of being under the power of Satan. Such cynicism and unbelief is motivated by a refusal to accept the evidence of God that is right before them. Essentially, their problem was a lack of faith. Without faith there can be no forgiveness of sins. The thing that is unforgivable is their willful unbelief. (see 1 Jn. 5:16 & Heb. 6:4-6)
I believe that the same is true today. Anyone who willfully chooses to disobey God and does not believe is not going to be saved. So, what about someone who walks away and then returns? The question is does that person now have faith? If so then they can be forgiven. Prodigal son. I don't believe that God cares as much where you've been as where you are. He is not as concerned as much with what you have done, but what you are doing. And that goes both ways. You can't become a christian years ago and then walk away from God and expect to be in good standing with Him at judgment, in the same way you will not be judged by what you did if you are now walking in faith.
I also found this interesting. There are a number of sins against the Holy Spirit like Rebellion (Isa. 63:10), Lying (Acts 5:3-9), Resisting (Acts 7:51), using the Spirit for Selfish Gain (Acts 8:18-22), Grieving (Eph. 4:30), Quenching (1 Thess. 5:19), Disobedience (Heb. 10:29). Blasphemy is the only of these that is unforgivable.
I will continue to think and study through this difficult passage and maybe we can get together again to discuss it.
grace & peace.