The whole counsel of God does not include pitting scripture against scripture. We need to properly harmonize scripture scripture in order to reach the proper conclusion on doctrine.
You say 1 John 2:19 means they weren't saved.
That's pitting scripture against scripture.
My doctrine does not do that.
1 John 2:24 actually supports my argument. If what you heard from the beginning abides in you (descriptive of genuine believers) you will also abide in the Son and in the Father. *Also see 1 John 4:13.
"24 As for you, let that abide in you which you heard from the beginning." - 1 John 2:24
That is not descriptive.
We know it's not a descriptive passage, just by the simple fact that the believing Galatians left. Apparently, 1 John 2:24 was not very 'descriptive' of those genuine believers. Your doctrine pits scripture against scripture.