What did the early church fathers have to say about “eternal security” or “assurance of salvation” I am trying to find out what the early church fathers had to say about “eternal security” or “assurance of salvation”.  By that, I refer to the following Bible verses:

To Him who is able to keep you from falling and to present you before his glorious presence without fault and with great joy... (Jude 24)


...whoever believes in him shall not perish but have eternal life” (John 3:16)


My sheep listen to my voice; I know them, and they follow me.  I give them eternal life, and they shall never perish; no-one can snatch them out of my hand (John 10:27-28).


And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption (Ephesians 4:30)


For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord (Romans 8:38-39).

From verses such as these, Protestants understand that our eternal security is purchased by Christ, promised by the Father, and sealed by the Holy Spirit.  This assurance is experienced by Christians who have the indwelling of the Holy Spirit, whose lives have been transformed as evidence of the new birth and who live for Christ Jesus and who are prepared to die for Him – born-again Christians.
I say this not to promote a particular belief but to clarify what I mean by expressions like “eternal security” and “assurance of salvation”.  Neither do I wish to enter into a discussion on the theology.  I simply want to know what the early church fathers had to say on this subject.
Below is a summary from an article I found on the subject of 'Once saved, always saved' which is as close as I could find to the terms above in regard to the early fathers.
The whole article quotes from :

Justin Martyr 100-165
Shepherd of Hermas 155-180
Irenaeus 120-200
Tertullian 150-220
Origen 185-254
Cyprian 200-258
Augustine 354-430

Based on the quotes listed in the article, the writer comes to this conclusion (and it is my own conclusion also, from what is quoted) :

These men wrote from about A.D. 100 – 250. We do not find any statements to the effect that once a Christian is saved, he or she is always saved. But we do find a consistent belief, except for a few instances, that faith and works go together. This is consistent with the teachings of the Bible.


The earliest statement regarding “once saved always saved” comes from Augustine (A.D. 354-430).


It was left to Augustine to speak a clear word for perseverance in pre-Reformation times. Starting with predestination, he saw that election to eternal life inevitably involves final perseverance. Since salvation is always God’s gift, he entitled his work on perseverance On the Gift of Perseverance. He denied, however, that the believer can have any assurance of his final salvation. Carl F. Henry. Basic Christian Doctrines. Baker Book House, 1962.


It is important to note that the doctrine of “Once Saved Always Saved” did not appear in the literature of the church until the Reformation period. A review of the existing literature from the early church fathers suggests that most of them believed faith and works must both exist for a person to be a true Christian. While no person is perfect, the pattern of life must be present. Only a few seem to believe that a person can lose his or her salvation by disobedience. But it is also possible that they are only observing the biblical truth stated in James 2:17 and 1 John 2:19.


What is most important is, “Does the Bible teach, ‘Once Saved Always Saved.?'” The opinion of the early church fathers does not constitute truth. The early church fathers were not inspired authors. But Jesus and the apostles were. Jesus did not teach and the Bible does not teach that once a person believes in Jesus Christ he or she is going to heaven regardless of what he or she does in the future. James 2:26 captures the truth that faith and works go together. A true Christian will believe and obey. A true Christian will not leave the faith. Someone who claims to believe and lives like the world or leaves the faith is a liar, and 1 John 2:4 says the truth is not in him or her. However, we must remember that only God knows if one has actually left the faith. We do not see as God sees. The statement “Once Saved Always Saved” is misleading. It should be worded as follows, “Saved Only Once” or “Once Truly Saved Always Saved.” Once God selects people for salvation they have been selected and they will not depart from the faith. Those who have been truly saved will never depart from the faith.


The Nicean Creed does not address this subject.

The Primitive Church - from NeverThirsty.org