I know.
Neither, I'm sure, would most Christians.
But that wasn't my point. Jesus said in Matthew 12 that whoever says a word against the Son of Man will be forgiven, but whoever blasphemes the Spirit, won't.
If they had been the same, Jesus would have said, "anyone who speaks against me IS blaspheming the Spirit - and cannot be forgiven. But he didn't".
No, not really.
Peter had followed Jesus for 3 years. He had seen miracles, he had been sent out to drive out demons, he had seen the transfiguration and at least 2 people raised from the dead, he had walked on water. He had received a special revelation that Jesus was the Christ, the Son of God.
Jesus said that Peter was going to deny him. Peter said, "not me; even if I die, I won't deny you". Yet when he was asked, 3 times, "surely you were with Jesus?", he denied it, 3 x with curses.
It doesn't matter if it was his belief.
You said that whoever denies Jesus blasphemes the Spirit and cannot be forgiven- Peter denied Jesus, and was forgiven.