The Blasphemy of the Holy Spirit

The grace and love of God are so foundational to the Christian faith that they are essentially axiomatic. And yet, in Matthew 12:22-37 Jesus says that there is a sin that will not be forgiven, either in heaven or on earth. What is this sin, and how does it fit with what we know about God's forgiveness? Ryan explains in the following messege entitled "The Blasphemy of the Holy Spirit."