First Timothy 4:1
Kenneth S. Wuest Translation
But the Spirit says expressly that in the last strategic, epochal periods of time some will depart from the faith.
DEPART (Greek Definition) 868 APHISTẼMI; from APO. The word is translated as "depart." Rather, the word expresses standing alone in contr. to PISTEUõ 4100, to believe. This does not refer to those who had at one time been believers, but to those who refuse to believe, who stand aloof, alone [also read Hebrews 3:12]. This does not mean that they once belonged to God and now they no longer belong to Him, but rather that they stood away from God, never having belonged to Him.
THE FAITH (Greek Definition) PISTIS, confidence in certain divine truths.
This verse does not say "departed from salvation". The context says that some will be departing from doctrines. Depart means standing alone in Greek. It is an apostasy. They profess something. Those who "departed" are unsaved people. See hypocrisy of liars in the hypocrisy of speakers of lies in 1 Timothy 4:2.
Notice this: chapter 3:16 (believers) --> Chapter 4:1 (unbelievers) --> the end of verse 3 (believers), "For those... who are believers and who have a precise experiential knowledge of the truth."
DEPART FROM THE FAITH does not mean they were ever saved, but simply they have professed to be Christians. They knew about the Lord Jesus Christ and have been told that He is the only Savior. They professed for a time to follow Him, but they apostatized from the Faith (doctrinal faith; not from salvation but from teaching) because they have never been in faith. Read John Neilson Darby version for apostasy written in the text.
chapter 4Verse 6, "constantly reminding the brethren of these things." Yes, we are putting forth great efforts against opposition (4:1), because we have set our hope permanently upon the living God who is the Savior of all men, especially of believers (verse 9-11).
Chapter 4:12 Paul says to Timothy, "keep on becoming an example of the believers."
BAD CONDUCTS FROM CHRISTIANS:
Chapter 1: 3-4 Wrong teaching from Christians
Chapter 5: 3 & 10 Did not provide financial support for his own family
Chapter 5: 11-13 Younger widows disloyal to their commitment to the local assembly
Chapter 5: 17-25 Elders (overseers) who have previously sinned
Chapter 6: 3-10 Love of money in their Christian lives
Chapter 6: 17-19 Wealthy Christians who are highly minded; trusting money more than God
Because some Christians follow wrong teachings from the enemies or from their own ideas, concerning the Faith (not about salvation but teaching) they have suffered shipwreck "...whom I have delivered over to Satan in order that they may be taught not to be blaspheming" (1 Timothy 1:19-20). If these people are not saved, Paul will never say "I have delivered over to Satan," because they would belong to him (Satan) already. But since they belong to Christ, they have to be taught a lesson in order for them to turn away from the snare of the devil.
Let the glory to be God alone. "The Lord will keep me safe and sound for His kingdom, the heavenly one, to whom be the glory forever and ever. Amen" (2 Timothy 4:18). Whatever the situation concerning the Faith (doctrinal), that will never affect my entry to heaven because it is already kept by God for me to be there. I am not the Shepherd, I am the sheep on the Shepherd's shoulders,that's why I believe that HE KEEPS ME.