Revelation 14:11And the smoke of their torment will rise for ever and ever. There will be no rest day or night for those who worship the beast and its image, or for anyone who receives the mark of its name
The verse above implies that those who take the mark can’t repent. What did Jesus say the only sin you can’t repent from is?
Matthew 12
The Unpardonable Sin
31 “Therefore I say to you, every sin and blasphemy will be forgiven men, but the blasphemy against the Spirit will not be forgiven men. 32 Anyone who speaks a word against the Son of Man, it will be forgiven him; but whoever speaks against the Holy Spirit, it will not be forgiven him, either in this age or in the age to come.
Jesus teaches that rejection of who the Holy Spirit is, is the unforgivable sin, thus a literal mark contradicts John 3:16 that whoever believes will be saved
The mark is symbolic for unrepentant rejection of the Holy Spirit