Do you believe the great tribulation in Matthew 24:21 has been fulfilled or is this a future event?
Do you believe in a future literal human Man as the (Man of Sin/Antichrist)?
I think it is being fulfilled One like never before or ever again.
The man of sin is mankind under the influence of the god of this world (Satan) . Cain the first he slew his brother the first martyr. Peter another example who fell in false pride forbidding the work of the gospel .He was used as a demonstration of one who apposed the work of Christ our Lord .working in the Son of man Jesus the apostle. He was forgiven of his blasphemy against the Son of Man Jesus, the prophet and apostle .
Blasphemy after he left disappeared out of sight is not forgivable.