Who assured you of that? And when did they do so?
I think Paul noted something about the security of the believer.
13And you also were included in Christ when you heard the message of truth, the gospel of your salvation. When you believed, you were marked in him with a seal, the promised Holy Spirit, 14who is a deposit guaranteeing our inheritance until the redemption of those who are Gods possessionto the praise of his glory Eph 1:13-14
Another cherry-picker.