SOME WILL FALL AWAY FROM THE FAITH
1Timothy 4.1
"Some will fall away from the Faith."
As it have been commented previously, no one knows his or her salvation until the Book of Life will be open. (Revelation 20.12.15, 21.27). But before it happens we rely only on our HOPE for our Salvation, and our Faith in Christ must be proven by our Good Deeds in the Name of Christ. We must be worthy of the Blood of Christ, His Sacrifice for us, and His Forgiveness of our sins, otherwise His Sacrifice and His Salvation would not come to those who is not of His flock.
Paul already knew and predicted the fallout of many Christians long before it will happen in mass, because in his time Paul already saw how many people are fallen away from Christ. These are those who at first accept Christianity, but then after a while turned around and went back to the world. They betrayed their Christian principals and ideals and went back to the world to seek the opportunities in wealth and in pleasures (1Timothy 6.10).
Even worse, by staying in the church, such people converted the church into a business of making money and ruin the true Faith of many who decided to follow them (Isaiah 56.6-7) (Jeremiah 7.9-11) (Matthew 21.13) (Mark 11.17) (Luke 19.45).
Such people who fall away from the Faith in Christ can be compared to Esau, who sold his first birth right for a bowl of pottage (Genesis 25.29-34).
The Parables of Christ also reflect this issue and describe different Faith in different people (Matthew 13.1-9) (Mark 4.1-9) (Luke 8.4-8).
When Christ said, "He who is not with Me is against Me, and he who does not gather with Me, scatters." (Matthew 12.30) (Luke 11.23), it meant not only those who are in the world, but also those who are fall away from their Faith in Him.
No one can Serving Two Masters: (Matthew 6.24) (Luke 16.13), means serve the Christ and at the same time live like the world live (1Timothy 6.10). For this reason, Christ also said, "for many be called, but few chosen." (Matthew 20.16, 22.14) (Luke 14.24).
So, those who preach, "whoever saved is saved," actually preaching truth but they twisted the meaning and applied it as assurance and not as Hope. Only GOD knows who is saved and who is not and this is the end of all arguments. Those who preach this false doctrine, with assurance that all are saved who believe in Christ, preach falsehood and give False Hope, because far not everyone who believe in Christ is following Him.
"Believe in Christ and be saved" is very general terminology that calling all people to Christ. But far not all who believe in Christ are truly believers and are saved, because "believing in Christ" means to follow Christ in everything He has preached and teach and live according to His Statutes and Commandments. Follow the Christ also means obey His Gospel and live by it, which of course many "Christians" do not do, but only claim that they are Christians.
And even demons believe and shudder before Christ. Do they also saved? (James 2.19) (Matthew 8.29) (Mark 1.34) (Luke 4.34.41).
Everybody will be judged according to their Deeds and not according to their words. Faith without Good Works in the Name of Christ is useless (James 2.14-26), and many claim that they have Faith in Christ but have no Good Deeds in His Name, and so, if they have No Good Deeds in the Name of Christ, they do not have Christ, they are alone in this world.
The statement of Paul in his Epistle to Hebrews completely destroys the false narrative of assurance of salvation just for believing in Christ, because it said that those who have been enlightening in Gospel of Christ and then fall away for whatever reason, impossible to turn back to Christ (Hebrews 6.4-6). They lose their one and only Chance and Hope for Salvation and will perish together with the rest of the world.
Besides our Faith we are also have a conscience, and our own conscience plays essential role in our Faith in Christ. If our own conscience is weak and did not attach itself to the principals and ideals of Christ, this also mean failure in Faith once obtained through the Christ's Gospel (1Timothy 1.19).
We first conscientiously driven to the principals and ideals of Christ and then explore and adapted His way of life that in return generated true Faith in Him. Those who has weak conscience or not have it at all, also may attached themselves to ideals of Christ, but they have no Faith due of lack of conscience, and spent their life as false Christians that do not benefit them.
GOD constantly tests our Faith in Christ (James 1.2-8) without our knowledge, and those who fail to follow His Statutes and His Commandments of His Spiritual Gospel, such "Faith" is nullified, it is "dead," and does not lead to Salvation.