Saint Paul didn't think so.

1 cor 4:4 I am not conscious of anything against me, but I do not thereby stand acquitted; the one who judges me is the Lord.
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Therefore, do not make any judgment before the appointed time, until the Lord comes, for he will bring to light what is hidden in darkness and will manifest the motives of our hearts, and then everyone will receive praise from God.

1 cor 9:27 No, I drive my body and train it, for fear that, after having preached to others, I myself should be disqualified

Not only did paul not think he was ***ured of salvation but he also thought that he could lose it.

Rom 11:22 See, then, the kindness and severity of God: severity toward those who fell, but God's kindness to you, provided you remain in his kindness; otherwise you too will be cut off.

Paul also warn us of us too being cut off

Heb 10:26 If we sin deliberately after receiving knowledge of the truth, there no longer remains sacrifice for sins
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but a fearful prospect of judgment and a flaming fire that is going to consume the adversaries.

Again we are warned that deliberate sin results in us being cut off.

He who endure till the end will be saved Matt 24

I know there is alot of scripture that says no one will take us out of Gods hands. I would say to that aslong as we remain in the eternal sonship of christ thats true but not if we turn away in sin.