If your enduring to keep saved, Your earning salvation.
By your reckoning... which is without scriptural basis, or even sound reasoning. You certainly aren't going to be saved if your faith doesn't endure, and we would not be told to endure if we had no part in it, even if your faith enduring is... by faith.
If they were among us, then they must have said they believed. A non believer is not part of us..
It doesn't say they professed to believe, or that they were part of the church. It says their departure (not
apostasia)made it clear they were not believers. You can be with a teacher of the gospel for some time, learning the doctrines and beliefs of the church before you decide you don't believe and "go out from them". If you depart from there, and go around to other churches denying Jesus trying to deceive people, guess what- that will reveal you didn't believe what they taught.
An apostate is an ANTICHRIST.
They DENY JESUS/
Not every apostate goes out from the church, though. and they don't all openly deny Jesus, and they don't necessarily go around as false teachers either. That is what these anti-christs were doing. You can see that is what he is talking about and not people that simply left the faith and went about minding their own business.
My friend. A PERSON WHO REJECTS CHRIST IS A NON BELIEVER, he Denys christ, and as such is an antichrist.
Again, it's not a blanket statement. Even if someone who leaves the faith is an anti-christ: that's not what verse 19 is about. It's about specific people that were going around to deceive the church. THOSE people went out from the church (a physical departure not "
apostasia"). THEIR departure made it clear they did not believe. That's all it says. He is talking about something that actually happened, he's not making a principle out of it.
There's nowhere in the bible where the apostles are like "HEY GUYS DON'T CONCERN YOURSELF ABOUT BELIEVEING IN JESUS, REMAINING IN CHRIST, DOING GOOD WORKS, WE DON'T HAVE TO DO THAT! GOD DOES IT FOR YOU. Its not there.