He that overcometh - The conqueror who has stood firm in every trial, and vanquished all his adversaries.

Shall not be hurt of the second death - That is, an eternal separation from God and the glory of his power; as what we commonly mean by final perdition. This is another rabbinical mode of speech in very frequent use, and by it they understand the punishment of hell in a future life.

The Epistle to the Church at Pergamos

that hath. See on ver.

Revelation 2:7 He that has an ear, let him hear what the Spirit said to the churches; To him that overcomes will I give to eat of the tree of life...

Revelation 13:9 If any man have an ear, let him hear.

the second.

Revelation 20:6,14 Blessed and holy is he that has part in the first resurrection: on such the second death has no power...

Revelation 21:8 But the fearful, and unbelieving, and the abominable, and murderers, and fornicators, and sorcerers, and idolaters...

Declension from First Love
But further, Christ says, "I know thy patience." Now there be some that labour, and they do it well. But what does hinder them? They only labour for a little season, and then they cease to work and begin to faint. But this church had laboured on for many years; it had thrown out all its energies--not in some spasmodic effort, but in a continual strain and unabated zeal for the glory of God. "I know thy patience." I say again, beloved, I tremble to think how few out of this congregation could win …
Charles Haddon Spurgeon—Spurgeon's Sermons Volume 4: 1858

The Dialogue against the Luciferians.
Introduction. This Dialogue was written about 379, seven years after the death of Lucifer, and very soon after Jerome's return from his hermit life in the desert of Chalcis. Though he received ordination from Paulinus, who had been consecrated by Lucifer, he had no sympathy with Lucifer's narrower views, as he shows plainly in this Dialogue. Lucifer, who was bishop of Cagliari in Sardinia, first came into prominent notice about a.d. 354, when great efforts were being made to procure a condemnation …
St. Jerome—The Principal Works of St. Jerome

The Laodicean State of Christendom.
In Revelation two and three we have seven Epistles addressed to the seven churches in Asia. These Epistles--in keeping with the nature of the book in which they are found--are prophetic in their scope. They record the sentences of the Divine Judge who appears in the midst of these churches (see 1:13-20) inspecting and passing decisions. They contain a panorama of the Church's history. They give us a complete outline of the entire course of the Christian profession, of going from bad to worse, until …
Arthur W. Pink—The Redeemer's Return