Almost everything I have argued about ownership can be accepted without believing in God.
You do not need scripture to notice that treating yourself as an asset makes you ill. All of it is observable. All of it holds on its own terms.
It just does not do anything.
Because there is one question that the secular version cannot answer, and it is the only question that matters at the point of action. Not is letting go better. That is settled and everybody already agrees. The question is: why should I?
Marcus Aurelius ran the largest empire in the world and wrote privately that everything he had was on loan and should be held lightly because it would be recalled without notice.
The Stoics were not wrong. They were right, they were early, and they wrote it down with more discipline than most people manage.
And Rome carried on exactly as before.
Mindfulness has been in the wealthy world for forty years, mapped and researched and packaged, and consumption has risen throughout. Minimalism produced a great deal of furniture.
These are not failures of communication. Everybody heard.
Here is the structural problem. Take custodianship as a philosophy and nothing else. Hold things lightly. Need less. Share more. Release the grip.
Now ask what happens to the man who declines.
He hoards. He exploits where exploiting pays. He lives out his seventy or eighty years accumulating, and he does rather well, because the system rewards it. And then he dies.
And the custodian who gave everything away also dies.
If that is the whole picture, then the two of them arrive at the identical destination by different routes, and the exploiter's reasoning is airtight. Why give when taking works? The grave does not audit.
Which means custodianship, as a philosophy, is optional. A preference. A disposition that some people find appealing and others do not. And what happens to any ethic that is optional is entirely predictable: it is adopted by the people who were already decent and ignored by the people with the most to gain from ignoring it.
You do not talk somebody out of an existential grip by winning an argument. The grip is not held in the part of the person that arguments reach.
So what would be strong enough?
Marcus Aurelius had the insight and no mechanism.
The insight was never the missing piece. We have had the insight the whole time.