If I understood correctly, the only unforgivable sin mentioned in the Bible was blasphemy in regards to those alive during the short time that Jesus walked the earth. When Jesus hung on the cross and said “Father forgive them, for they know not what they do” wouldn't all of his wrong doers been forgiven?
Jesus’ statement on the cross was not a blanket statement of forgiveness for all humanity on earth or even for all Israel in that day. We must interpret Scripture based on its context, and from the context of Jesus’ statement, He was speaking about the handful of Roman soldiers carrying out His execution. In fact, we see evidence that Jesus’ request was granted for at least one of the soldiers:
Elsewhere, Jesus makes clear that the Pharisees and many in that generation of Israel would not be saved because of their unbelief:
Clearly, not all Israel was saved in that day when Jesus uttered the words “forgive them”. The “them” Jesus spoke about were the Romans soldiers attending to His crucifixion.