Jesus makes it clear that my decisions now will lead to actions that will set my future for the rest of eternity. If, when pressed before others to admit that I have faith in Jesus, I must not deny him, doing so will bring shame before the heavenly hosts in my future. Note though that Peter denied Jesus three times when Jesus was arrested as Jesus foretold, and Peter was forgiven by repentant Peter as Jesus said in verse 10.
However, Jesus promises that if anyone blasphemes against the Holy Spirit will not be forgiven in verse 10. Matthew 12:31 and Mark 3:28:29 are similar claims Jesus makes about this subject. The context of all three passages clarifies that the unforgivable sin is claiming the work of the Holy Spirit is evil and the work of Satan. This is what the Pharisees and the teacher of the law were stating about the work of Jesus (Mark 3:30).
