I agree that the Bible teaches that a believer can fall away from the faith (apostasy) or that a believer can die spiritually as a result of dying physically in unconfessed grievous sin (like hate, lying, and lusting, etc.), but 1 John 2:18-19 is not one of these passages. 1 John 2:18-19 is referring to gnostic believers that held to heretical views (Such as denying sin's existence - 1 John 1:8 (kind of like the Christian Scientist), and denying that Christ came in the flesh, i.e. a rejection of Christ's deity - 1 John 4:3 (like the Unitarian). They were never of the true body of believers to begin with even though they went out from the apostle's care of hearing God's message. These individuals were never saved or born again spiritually.
But this does not mean there are not other passages or verses that speak about how a believer can fall away. For...
Paul teaches that we can fall away from the faith:
- We can fall from grace (Galatians 5:4).
- We can be moved away from the hope (Colossians 1:23).
- We can be a castaway (1 Corinthians 9:27).
- We can be cut off just like the Jews if we do not continue in God’s goodness (Romans 11:20-22).
- We can sow to the flesh and reap corruption instead of sowing to the Spirit which reaps everlasting life. (Galatians 6:8) (Also see: Romans 8:13).
- We can deny God by a lack of good works (Titus 1:16).
- We can shipwreck our faith (1 Timothy 1:19).
- We can deny the faith and be worse than an infidel if we do not provide for our own household (1 Timothy 5:8).
- We can err from the faith and pierce ourselves thru with many sorrows if we love and covet after money (1 Timothy 6:10).
- Hymnenaeus and Philetus have overthrown the faith of some (2 Timothy 2:18).
Here is a list of believers who have forfeited their salvation:
Saul (1 Samuel 16:14) (1 Samuel 31:4)
Demas (2 Timothy 4:10)
The Prodigal Son (Luke 15:11-32)
Judas Iscariot (Psalms 41:9) (Luke 6:16) (Acts of the Apostles 1:25)
Hymenaeus and Philetus (2 Timothy 2:17-18)
Unnamed Christians destroyed by false teaching (2 Timothy 2:17-18)
Many Unnamed Disciples (John 6:66)
Some Younger Christian Widows (1 Timothy 5:14-15)
Some Christians Eager For Money (1 Timothy 6:8-10)
Ananias and Sapphira (Acts of the Apostles 5:1-11)
And here is a list of potential fallen believers:
The Servant Who is Not Looking For Him (Luke 12:45-46)
Recent Convert Who is a Potential Spiritual Leader (1 Timothy 3:6)
The Unforgiving in Heart (Matthew 6:14-15)
Luke Warm Unrepentant Believer (Revelation 3:14-22)
Fruitless Christians (John 15:1-10) (Matthew 25:14-30)
Widows That Live in Pleasure (1 Timothy 5:5-6)
Believers Whose Seed Fell Upon the Rocks (Luke 8:13)
Believers Whose Seed Was Choked by Thorns (Matthew 13:22)
Gentile Believer Who Did Not Have on a Wedding Garment (Matthew 22:1-14) (Revelation 19:7-8)
The Potential Fellow Believer Who Erred From the Truth & Was Converted Back (James 5:19-20)
Many think that if you have been saved at one point in time in the past, and you will always be saved. But the Bible teaches that...
We need to endure in our faith to continue to be saved:
"But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin. For we are made partakers of Christ, if we hold the beginning of our confidence stedfast unto the end;" (
Hebrews 3:13-14).
"Blessed is the man that endureth temptation: for when he is tried, he shall receive the crown of life, which the Lord hath promised to them that love him." (
James 1:12).
"But he that shall endure unto the end, the same shall be saved.” (
Matthew 24:13).
"...be thou faithful unto death, and I will give thee a crown of life." (
Revelation 2:10).
"He that hath an ear, let him hear what the Spirit saith unto the churches; To him that overcometh will I give to eat of the tree of life, which is in the midst of the paradise of God." (
Revelation 2:7).
"He that hath an ear, let him hear what the Spirit saith unto the churches; He that overcometh shall not be hurt of the second death." (
Revelation 2:11).
"He that overcometh, the same shall be clothed in white raiment; and I will not blot out his name out of the book of life, but I will confess his name before my Father, and before his angels." (
Revelation 3:5).
"Keep yourselves in the love of God, looking for the mercy of our Lord Jesus Christ unto eternal life." (
Jude 1:21).
What is enduring (or overcoming) in the faith? It is being faithful or living holy by the power of God working in you. It is obedience to the Lord's commands, and not justifying grievous sin.
Anyways, I hope this helps, and may God bless you this fine day.
With loving kindness to you in Christ,
Sincerely,
Jason.