Here is what 1 John 2:19 actually says"
"They went out from us, but they did not really belong to us. For if they had belonged to us, they would have remained with us; but their going showed that none of them belonged to us."
When we look at the whole verse instead of extracting part of it and trying to make it say what John never meant, we see that he says, "If they had belonged to us, they would have remained with us". This means that they didn't belong to them at all, ever, and did not stop belonging to them just when they decided to leave. He says that if they really belonged to them, they would have stayed, but the fact that they left showed that they never belonged in the first place.
It is important that Scripture is quoted correctly for what the writer actually says and means, instead of injecting a false meaning into it. Peter says that some are twisting the words of Paul to their own destruction. This is the possible outcome of those who misquote and twist the Scripture to support their own opinions.
1)
"If they had belonged to us, they would have remained with us". If this means a person NEVER belonged to the church then all this verse proves is that one who was never saved...was never saved. It does not prove that one who is saved cannot fall away.
2) John is talking about specific individuals 'they'. Again, John wrote "
They went out from us, but they were not of us;". John did NOT write
"ALL who go out from, but ALL was never of us"...this is an assumption added into the verse. Therefore it cannot be applied universally to anyone/everyone who leaves the church, quits the faith..it applicable only to this case. For there are examples in the NT of those who fell away becoming lost in the NT along with many admonitions and warning about falling away:
John 6:66-67 "From that time many of his disciples went back, and walked no more with him. Then said Jesus unto the twelve, Will ye also go away?"
The word "also" means likewise or in the same manner. Jesus therefore is saying that it would be possible for His own Apostles to also/likewise go back and follow Him no more. One did, Judas. But if all 12 turn back and followed Christ no more does that prove they were never really saved to begin with? Of course not. On the other hand, if it were impossible for the Apostles to turn and follow Christ no more, then Christ's question is implying an untruth, a lie.
3) one such warning/admonition is found in 1 John 1:24 "
Let that therefore abide in you, which ye have heard from the beginning. If that which ye have heard from the beginning shall remain in you, ye also shall continue in the Son, and in the Father." John uses the word "therefore" tying verse 24 with what was just said. This command in this verse logically implies that the Christian can let the word of God slip from Him where then he would no longer continue in the Son. If not, then this has no logical meaning.
"
They went out from us, but they were not of us; for if they had been of us, they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us."
(A)--------------------------(B)-------------------------(C)
What in 1 John 2:19 prevents these people, whom John is talking about, becoming Christians at point (A) and remaining faithful until point (B) when they let God's word slip from them being deceived by false teaching of the Gnostics? Then they no longer belonged to us at point (B) and continue to not be of us all the way up to when they went out from us at point (C). This scenario gives sense to the warning/admonishment in verse 24 to Christians to let the word of God continue to dwell in them.
".
..but they went out, that they might be made manifest that they were not all of us."
"not' does not mean "never".
Break down of the context:
(a) "
They went out from us,"
This can mean:
1) they were never of us
2) they were once of us but they did not let God's word continue to abide in them.
(b) Verse 24 "
Let that therefore abide in you"
The command implies that a Christian might not let God's word abide in him and he will then deny the Son and have not the Father, verse 23.
(c) Verse 24 "
If that which ye have heard from the beginning shall remain in you, ye also shall continue in the Son, and in the Father." The word "if" is a conditional word, again implying that the Christian may NOT let God's word continue in them.
Therefore we now know that verse 19
CANNOT imply that it is impossible for a Christian to not ever let God's word dwell in him...for it certainly is possible according to verse 24.
(d) verse 25 "
And this is the promise that he hath promised us, even eternal life."
From v25 we see that eternal life is a promise, NOT an UNconditional guarantee no matter what the Christian does. This promise IS CONDITIONAL upon the Christian letting God's word continue to abide within him whereby the Christian continues to abide in the Son of verse 24.
(e) "
These things have I written unto you concerning them that seduce you."
This verse implies the Christian CAN be seduced, else it makes no sense and is a lie.
Verses 24-26 is NOT written to those that went out, but to those Christians that remained, the "true" Christians as you might call them.
(f) conclusion: verse 19 cannot be taken as an absolute rule that applies to ALL but an example that applied only to these people John was talking about.
Either these particular people John writes about:
1) were never of us
2) they were of us but did not let God's word abide in them and were seduced.
And neither 1 nor 2 prove OSAS, does not prove that departure means never of us.