Dr. Tony Badger, author of Confronting Calvinism, says this about the so-called Perseverance of the Saints: 

Not a single passage of Scripture…demonstrates that one who believes in Christ for eternal life…must perform properly and remain morally and doctrinally pure…until the end of his physical life so as to…prove that he is forever God’s child. Contrarily, the Bible is replete with examples of regenerate people failing in both doctrine and morals (p. 283).  

Badger’s point is that eternal security is true whether a believer perseveres or not. It is not guaranteed that a believer will persevere. If he does not, he will miss out on eternal rewards such as ruling with Christ, but his eternal destiny will be unaffected. He remains a child of God, just as the Lord promised in John 3:16 and many other texts (e.g., John 4:10-14; 5:24; 6:35, 37, 39, 47; 11:25-27).  

In my book, Is Calvinism Biblical? (ICB) I consider two passages that disprove the Perseverance of the Saints: Revelation 20:11-15 and John 11:25-27.  

Revelation 20:11-15. According to these verses, all the unbelievers of all time will be “judged according to their works, by the things which were written in the books [of deeds]” (v 11). Their works will determine the degree of tolerable torment (Matt 10:15; 11:22) each one has earned. However, no one will be cast into the lake of fire because of his works. Instead, “anyone not found written in the Book of Life was cast into the lake of fire” (Rev 20:15). One gets into the Book of Life by believing in the Lord Jesus for the everlasting life He promises. Perseverance is not an issue at the Great White Throne Judgment of Rev 20:11-15.  

On page 120 of ICB I wrote:

If Calvinism were true, Rev 20:15 would read, “And anyone whose works failed to prove that he had genuinely believed in Jesus was cast into the lake of fire.” The issue would be what was found in the books, not what was found or not found in the Book of Life.  

Instead, according to Rev 20:15, the basis of eternal condemnation is not being found in the Book of Life. Works have nothing to do with that. The Book of Life contains a list of all who have everlasting life. All who lack everlasting life are cast into the lake of fire. All with everlasting life get into Christ’s eternal kingdom.  

We know from the Lord Jesus’ teaching what one must do to get into the Book of Life. He taught that who ever believes in Him has everlasting life and will never experience the second death of Rev 20:14 (e.g., John 3:16; 5:24; 6:35; 11:26, “shall never die” = “shall never experience the second death”).

Dave Hunt accurately comments, “Anyone who will spend eternity in the Lake of Fire (Revelation 20:14) has sent himself there by rejecting the salvation God has provided for him as a free gift of His grace” (What Love Is This? Calvinism’s Misrepresentation of God, Second Edition [Bend, OR: The Berean Call, 2004], 312).

John 11:25-27. The assurance of being glorified to live with the Lord forever in His kingdom comes by faith alone, apart from works (John 11:25). Assurance that one “will never die [spiritually]” is based solely on one’s believing in Him (“He who believes in Me will never die”). There is no mention or hint of perseverance in John 11:25-27.  

Calvinists interpret these verses to mean that whoever continuously believes until the very end of his life will be glorified and will never die spiritually. But that is an impossible interpretation for three reasons. First, it would mean that a person would not be born again until he persevered in faith to the end of his life. There would not be a single born-again person living on earth, since no living person has as yet “persevered,” according to Calvinism’s definition. Second, it would mean that the Lord misled people when He used illustrations such as drinking the water of life and never thirsting again, and eating the bread of life and never hungering again (John 4:10-14; 6:35). Third, the present tense in the indicative mood does not refer to continuous action. The context indicates what sort of action is involved. The contexts of John 3:16; 4:10-14; 5:24; 6:35-47, and 11:25-27 all show that one is eternally secure the moment he believes in Jesus.  

It should also be noted that “perseverance in faith” is not the same as “perseverance in good works.” Yet Calvinists say that one must persevere in both faith and good works in order to prove that he is born again (old style Calvinists) or to win “final salvation” (new style Calvinists).  

The Perseverance of the Saints is a Trojan horse. It allows someone to claim that they believe in eternal security while also saying that if you fail to persevere, you will end up in the lake of fire. There is no assurance of everlasting life for someone who believes that he must persevere in order to enter Christ’s kingdom and avoid eternal condemnation.  

Keep grace in focus and you’ll know that you are eternally secure whether you persevere or not.