[Theo]

If you can lose your salvation, that implies that you can earn your salvation.

And that implies that Christ’s sacrifice on the cross was indeed not sufficient to reconcile us with God.

Ah, but Christ’s sacrifice is sufficient.

[sausageseller]

If you can lose your salvation, that implies that you can earn your salvation.

Salvation is a gift from God. One can receive it but reject it later. Just as Paul told us.

"Work out your salvation with fear and trembling" (Philippians 2:12).

[GonzoII]

"If you can lose your salvation, that implies that you can earn your salvation."

Adam and Eve didn't earn their salvation, i.e., friendship with God but they did lose it and tradition does say they got it back. I don't agrre at all with your implication.