But God's word, in the original Greek, says
ei dunatos, which, though often translated as it is here, "if possible," literally means "impossible" in such a context, which is known in both English and Greek studies as a "negative adjective." The elect cannot be deceived. Period. A believer cannot "drift from the truth." He/she may drift from the
path, but not the truth. John summarizes the impossibility of "losing one's salvation" perfectly in his first epistle, though most fail to recognize it as such.
1 John 1,NASB
5 This is the message we have heard from Him and announce to you, that God is Light, and in Him there is no darkness at all.
6 If we say that we have fellowship with Him and yet walk in the darkness, we lie and do not practice the truth;
7 but if we walk in the Light as He Himself is in the Light, we have fellowship with one another, and the blood of Jesus His Son cleanses us from all sin.
8 If we say that we have no sin, we are deceiving ourselves and the truth is not in us.
9 If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness.
10 If we say that we have not sinned, we make Him a liar and His word is not in us. [Emphasis added]
The breakdown:
v. 5 -- God is light and no one lives in darkness who is in Him.
v. 6 -- Claiming fellowship with Him when we walk in darkness means we are not actually in Him, and never were.
v. 7 -- Walking in light -- doing good works, trusting in Him to lead and guide us, being transparent and intentional in our faith -- is the proof of His cleansing of our soul.
v. 8 -- Saying we have no sin is a denial of Christ and our need for His sacrifice, meaning we were never His.
v. 9 -- Confessing our sins daily keeps us in tune to His leading. We are already forgiven, so confession is for us -- keeping us focused -- not for Him, who died for
all our sins, not just the ones we were bearing at the time of our salvation, but even those we had not yet committed.
v. 10 -- Thinking we do not sin once we do have faith breaks fellowship with Him and indicates we have not been open to His teaching, which states all have sinned -- including those who believe Him for Who He is and what He has done for us.