There are two main positions on salvation. One is that if you accept Christ then you are not going to lose that relationship. The other position is that you can fall away and lose your salvation. You hold, or your community of faith holds to one of those positions.
What do you do with 2 John 9 (here @ Bible Gateway)?
How do you reconcile that passage with the view that one cannot fall away? If you hold the second view, does this passage support your position?
Take your time on this. Do not answer without validating your answer from other passages of Scripture.