Salvation by works, which Paul disproves in Galatians 3.
He will keep secure those who trust in Him, not those who trust in OSAS. He gets to define what "trust in Him" means and it is to continue in the faith. Never give up. Cling to him because you love him and you will obey him. Remember the woman who washed Jesus' feet with her tears.
He doesn't promise that. For one thing, those who trust Christ are not trusting OSAS. We trust Christ, not our doctrine. We believe we are secure because HE promised us that He sealed us with His Holy Spirit.
Ephesians 1:13-14 In him you also, when you heard the word of truth, the gospel of your salvation, and believed in him, were sealed with the promised Holy Spirit, who is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory.
Ephesians 4:30 And do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption.
Even if we grieve Him, we are still sealed by Him.
You didn't really address the last comment at all, much less really answer the questions.
It's not got to do with the doctrine and Scripture. It's got to do with WHY people want to believe so bad that they are not secure when God promises that we are.
I'm good with that.