John is talking to children of God who have the anointing of the Holy Spirit. That's a saved person. And he tells them that if they let the word remain in them they will remain in the Son and the Father
and the promise of eternal life (not rewards).
As for you, let what you have heard from the beginning remain in you. If it does, you will also remain in the Son and in the Father. And this is the promise that He Himself made to us: eternal life. 1 John 2:24-25
This makes it so osas can't say that vs. 19 just before this means what it means. But that doesn't matter. What we can take away from this with complete confidence is John's admonition to let the word of God remain in us. That's what is important. That is what matters. Solving the osas mystery is not important. Let's do what the Bible plainly tells us to do. That's what counts.