Theological writings
Jerome warned that those substituting fake interpretations for the actual meaning of Scripture belonged to the "synagogue of the Antichrist". "He that is not of Christ is of Antichrist", he wrote to Pope Damasus I. He believed that "the mystery of iniquity" written about by Paul in 2 Thessalonians 2:7 was already in action when "every one chatters about his views." To Jerome, the power restraining this mystery of iniquity was the Roman Empire, but as it fell this restraining force was removed. He warned a noblewoman of Gaul:
He that letteth is taken out of the way, and yet we do not realize that Antichrist is near. Yes, Antichrist is near whom the Lord Jesus Christ "shall consume with the spirit of his mouth". "Woe unto them," he cries, "that are with child, and to them that give suck in those days." ... Savage tribes in countless numbers have overrun all parts of Gaul. The whole country between the Alps and the Pyrenees, between the Rhine and the Ocean, has been laid waste by hordes of Quadi, Vandals, Sarmatians, Alans, Gepids, Herules, Saxons, Burgundians, Allemanni, and – alas! for the commonweal! – even Pannonians.
His Commentary on Daniel was expressly written to offset the criticisms of Porphyry, who taught that Daniel related entirely to the time of Antiochus IV Epiphanes and was written by an unknown individual living in the second century BC. Against Porphyry, Jerome identified Rome as the fourth kingdom of chapters two and seven, but his view of chapters eight and eleven was more complex. Jerome held that chapter eight describes the activity of Antiochus Epiphanes, who is understood as a "type" of a future antichrist; 11:24 onwards applies primarily to a future antichrist but was partially fulfilled by Antiochus. Instead, he advocated that the "little horn" was the Antichrist:
We should therefore concur with the traditional interpretation of all the commentators of the Christian Church, that at the end of the world, when the Roman Empire is to be destroyed, there shall be ten kings who will partition the Roman world amongst themselves. Then an insignificant eleventh king will arise, who will overcome three of the ten kings. ... After they have been slain, the seven other kings also will bow their necks to the victor.
In his Commentary on Daniel, he noted, "Let us not follow the opinion of some commentators and suppose him to be either the Devil or some demon, but rather, one of the human race, in whom Satan will wholly take up his residence in bodily form." Instead of rebuilding the Jewish Temple to reign from, Jerome thought the Antichrist sat in God's Temple inasmuch as he made "himself out to be like God."
Jerome identified the four prophetic kingdoms symbolized in Daniel 2 as the Neo-Babylonian Empire, the Medes and Persians, Macedon, and Rome. Jerome identified the stone cut out without hands as "namely, the Lord and Savior".
Jerome refuted Porphyry's application of the little horn of chapter seven to Antiochus. He expected that at the end of the world, Rome would be destroyed, and partitioned among ten kingdoms before the little horn appeared.
Jerome believed that Cyrus of Persia was the higher of the two horns of the Medo-Persian ram of Daniel 8:3. The he-goat is Greece smiting Persia.
Jerome opposed the doctrine of Pelagianism, and wrote against it three years before his death. Jerome, despite being opposed to Origen, was influenced by Origenism in his soteriology. Although he taught that the Devil and the unbelieving will be eternally punished (unlike Origen), he believed that the punishment for Christian sinners, who have once believed but sin and fall away, will be temporal in nature. Some scholars such as J. N. D. Kelly have also interpreted Ambrose to have held similar views considering the judgement of Christians.
Although Augustine does not name Jerome personally, the view that all Christians would eventually be reunited to God was criticized by Augustine in his treatise "on faith and works".