Well, eating the forbidden fruit didn't cause Eden to become corrupted. But yeah, let's not dwell on that.

I also agree with you that salvation cannot be lost. It's the obvious result of the fact that we are all already saved, always were, and always will be. But vast majority of people is simply not fully aware of that and thus rejects such notion. They all hope for something "better," while plain acceptance of here and now, exactly as it is, is more than enough to "become" irrevocably saved.

And while there are people who are good at faking, such resistance becomes pretty obvious once you fully surrender yours to the undiluted reality of present moment. From my experience, it's not that hard to find cracks in such counterfeit armor.

Naturally, I bet you can also imagine how it pans out, if someone resists in such denial to the bitter end. Well, talk about idiocy of self-inflicted hell that, up to that point, also inevitably spilled into the world through fruit of one's actions, desecrating God's perfect work.

But of course, if your idea of salvation is different, you may come to the conclusion that it's not possible to tell if someone is really lost, or merely not adhering in an obvious way to what the idea itself entails on the surface (like e.g. proclaiming some allegedly magical formula of allegiance, ritually immersing oneself into water, confession of sins in a particular setting, and so on).