In Mark 3:22-30 Jesus is accused by the religious leaders of being possessed by Satan. His careful response refutes the claim and then warns them of the unforgivable sin: blaspheming the Holy Spirit.  

It’s helpful to think of salvation in terms of two paths. Every person starts off on the “wide road” headed for destruction. When God reveals himself, we have the opportunity to respond to Jesus and enter the “narrow path” that leads to salvation.

Acts 10:36-43 (NLT) This is the message of Good News for the people of Israel—that there is peace with God through Jesus Christ, who is Lord of all…. Jesus went around doing good and healing all who were oppressed by the devil, for God was with him…. They put him to death by hanging him on a cross, but God raised him to life on the third day…. And he ordered us to preach everywhere and to testify that Jesus is the one appointed by God to be the judge of all—the living and the dead. He is the one all the prophets testified about, saying that everyone who believes in him will have their sins forgiven through his name.”

Col 2:13-15 You were dead because of your sins and because your sinful nature was not yet cut away. Then God made you alive with Christ, for he forgave all our sins. He canceled the record of the charges against us and took it away by nailing it to the cross. In this way, he disarmed the spiritual rulers and authorities. He shamed them publicly by his victory over them on the cross.

The unforgivable sin, then, occurs when a person rejects the true identity of Jesus and stays on the path of self-deception and sin. 

Mark 3:28-30 “I tell you the truth, all sin and blasphemy can be forgiven, but anyone who blasphemes the Holy Spirit will never be forgiven. This is a sin with eternal consequences.” He told them this because they were saying, “He’s possessed by an evil spirit.”