Believer says: 666 will be an end-time sign.
But skeptic says: Some say that end-time has come and gone! They say that in Revelation 13, the one whose number was 666 was Emperor Nero of AD 60s.
The name and title in Greek, Neron Caesar, when re-written in Hebrew letters, makes a total numerical value of 666.
Even the final “n” can be left out for a total of 616. And few manuscripts known to the second century Christian Irenaeus--a Christian intellectual--read 616. But Irenaeus believed in an Antichrist that was still to come, so he rejected the idea that the number could stand for Nero.
Nero committed suicide in AD 68. But, although it may sound rather strange, the church feared his eventual return! In his Sacred History (or Chronicle), the Christian writer Sulpicius Severus (c. AD 403) expresses the dread of some church intellectuals:
ii. 28: “Nero, the basest of all men, and even of monsters, was well worthy of being the first persecutor. I know not whether he may be the last, since it is a current opinion of many that he is yet to come as Antichrist.”
Revelation teaches that Satan’s assistant, the beast whose mark is 666, will recover from a moral blow and return from death. So there was the fear of Nero coming back.
A few manuscripts show even more numerical variations for Revelation 13:18!
Recap: There's strong chance the Antichrist was Emperor Nero, so the man whose mark was 666 came and went a long time ago.