“But he that shall blaspheme against the Holy Ghost hath never forgiveness, but is in danger of eternal damnation.” Mark 3:29

This has been touted as teaching the unpardonable sin. As scary as this may sound, the verse right before it is very encouraging:

“Verily I say unto you, All sins shall be forgiven unto the sons of men, and blasphemies wherewith soever they shall blaspheme.”

This reminds us of the promise in Acts 13:39: 
“By him all that believe are justified from all things.”

So what is this terrible sin to which Jesus claims there is not forgiveness?

Jesus said these things in response to the statement by the scribes in verse 22:

“And the scribes which came down from Jerusalem said, He hath Beelzebub, and by the prince of the devils casteth he out devils.” 
Apparently, the scribes had already blasphemed the Holy Spirit, yet Jesus did not condemn them at this time, but rather warned them of being in danger of a future judgment. So the blasphemy to which Jesus was referring as being without forgiveness was a continued blasphemy until the coming judgment.

What exactly did these scribes teach that was so bad? They attacked the person of Jesus Christ by saying that he was aligned with Satan, and they attacked the work of Jesus Christ by saying that He did His work by the power of Satan rather than the Holy Spirit. The attack was significant in that it denied the two things that a person must believe in order to have eternal life. It denied the person and work of Jesus Christ.

In similar manner, if a person does not believe that Jesus is God the Father who came to earth, he is denying the person of Jesus Christ, and if a person does not believe that Jesus’ death, burial, and resurrection is sufficient to save them and keep them saved, then they have denied the work of Jesus Christ. That person is also in danger of eternal judgment.

If you have never accepted the truths of the person and work of Jesus Christ by trusting Jesus’ death payment on the cross, all you Have to do is believe that Jesus is God the Father who came to earth to pay for all of your sin so you can go to heaven by what He did. Trust Him. He is trustworthy.