What is the Unforgivable Sin?

As I studied to preach on Mark 3:20-30, I gathered a few of the best definitions of blasphemy against the Holy Spirit.

• ESV Study Bible: It is attributing to Satan what is accomplished by the power of God – flagrant, willful, decisive judgment that the Spirit’s testimony about Jesus is satanic.
• Wayne Grudem: It is unusually malicious, willful rejection and slander against the Holy Spirit’s work attesting to Christ, and attributing that work to Satan.
• Dan Doriani: Blasphemy against the Spirit is the sober, clear-minded, deliberate rejection of Jesus—as a very agent of evil—despite full knowledge of his work and in the face of the Spirit’s full testimony of him.
• Kent Hughes: “It is the ongoing, continual rejection of the witness of the Holy Spirit to the Divinity and Saviorhood of Christ.”

Here is the way I tried to simplify it in my sermon:

Blasphemy against the Holy Spirit is a clear, deliberate, malicious repudiation of Jesus Christ by someone who should know better.

You can listen to my sermon here.