Answer: Yes. This sin is very similar to the sin of the Pharisees. Although they did not directly call Jesus the devil, they accused Him of being demon-possessed. (See John 8:46.) So for all practical purposes, they were saying that He was energized and controlled by Satan, which comes very close to calling Him “Satan.”
There are two things worth noting about the particular sin of calling Jesus “Satan.” First, such a person has been thoroughly deceived. He is living proof that the devil is a master deceiver. The Scriptures tell us that Eve was deceived by the serpent (2 Cor 11:3). For thousands of years Satan has been honing his skill, and nothing would give him greater pleasure than hoodwinking someone into thinking that Jesus, God in human flesh, was really the devil. What joy such a person must bring to Satan!
Second, as bad as this sin is, God will still forgive it. In 1 John 1:7, we are told that the blood of Christ cleanses from all sin! The Apostle Paul is a living demonstration of such forgiveness, for he describes himself as “once a blasphemer,” but he was shown mercy through coming to faith in Christ (1 Timothy 1:13,14). It is not too late to stop calling Jesus “Satan” and to start calling Him your Lord and Savior. “Believe on the Lord Jesus Christ, and you shall be saved,” no matter what you have been guilty of calling Jesus in the past (Acts 16:31).