Shortly after his historic meeting with Jewish elders in Rome, in A.D. 64, as reported in Acts 28, the Apostle Paul wrote a series of epistles — one to the Jews (the book of Hebrews) and seven to Gentile congregations. Among them was the letter to the Philippians, in which this passionate apostle wrote, "The Lord is at hand" (Phil. 4:5).
He wrote this incredible statement only seven years before the destruction of Herod's Temple. Why not? There was still time for Nero, the supposed Roman Antichrist, to commit the abomination of desolation, enslave the world and bring on the battle of Armageddon.
Even after the Jewish elders rejected Paul's message about their Jewish messiah, and his announcement that he was going to take the message of the Gospel to the Gentiles, the apostle was still convinced that Christ would soon return.
A decade before, in A.D. 54, Paul had penned his first two epistles (I&II Thessalonians), in which he taught the doctrine of the rapture and resurrection. In fact, all of the apostles were preaching on prophetic subjects, expecting Christ to return in their generation. It was a popular doctrine in the first century.
In Hebrews 3:9, Paul reminded the Jews that God only gave them forty years in which to repent. It is possible that Paul was alluding to the fact that Christ was crucified around A.D. 30, and that they only had about six more years to repent.
Nero was the Roman emperor at that time and, because his name added up to 666 in Hebrew gematria, many considered him as the prophesied Antichrist. Nero came to power on October 13, A.D. 54, following the death of Claudius — the same year that Paul wrote II Thessalonians 2:3&4, in which he mentioned the "man of sin ... the "son of perdition; Who opposeth and exalteth himself above all that is called God, or that is worshipped, so that he as God sitteth in the temple of God, shewing himself that he is God."
He is the emperor that had Paul beheaded on June 29, A.D. 66 — the same year that the Jewish revolt started in Jerusalem. However, two years later, Nero was deposed by a military coup and, facing execution, Roman historians claim that he committed suicide on June 9, A.D. 68.