People identifying Christ with Satan
I was reading The People's Bible for Mark, and as I was reading what the book said on Mark 3:20-30, I read that "when people deliberately identify Christ with Satan and speak of his work as satanic, the Holy Spirit can no longer do his work in their hearts, the work of bringing them to faith in Jesus Christ as their Savior." Does this mean that someone only has to say these words in ordered to commit the sin and be condemned, or does he have to think it in his heart as well? Can a believer who says these words lose his faith and condemn himself even if he did not believe that what he was saying was true?
Just as Christians speak of their faith (confess their faith) on the basis of what is in their hearts, so unbelievers speak on the basis of what is in their hearts. The sentence you quoted describes people speaking blasphemously about Jesus because of their identification of Christ with Satan. Such people are not speaking empty words; they are professing what their minds have concluded and their hearts have embraced. Jesus was not speaking of a Christian’s reckless conversation. In the context, he was warning against willful and malicious rejection of the gospel against better knowledge.
As Christians, we recognize that there is always room for our faith to grow. That is why we can identify so easily with the man who said to Jesus, “I do believe; help me overcome my unbelief!” (Mark 9:24)