In my mental model it's implied, since people are the image of God and so being humble towards them is being humble towards God (and I'm not sure there's a context where humility exists independently of other people).
Humility is also useful when alone. I think X is true but let me double check can easily save your life irrespective of a belief in god or the presence of other people. Using a checklist before flying for example is an important recognition of your imperfection. Measure twice cut once is again the same idea.
Yes, something along this line occurred to me after posting, but I'd agree with you. Integrity is also arguably a case where humility can come into play even when people don't notice.
The idea is that everyone has unifying motivations, often in a higher power, where they derive their personal sense of morality from. Whether religion, family, tradition, survival, knowledge, the invisible hand of the market, a love of humanity or life for its own sake, sheer pleasure, whatever.
The point is that regardless of the original intent of the Judeo-Christian text, it seems an admirable enough message that can be recontextualized easily enough to fit those of different ethical and theological viewpoints on this forum. No hair-splitting or holy wars necessary.
The allusion to Alcoholics Anonymous is that the “acknowledging a higher power” step, while commonly assumed as pushing crypto-Christianity, can be reinterpreted by each individual participant as their own unifying motivator.
The paradox of twelve steps is that you are supposed to consider yourself at powerless and submit to your higher power yet at the same time every failing is only down to you and resets all progress.
I make no claims about the program as a whole, I was just dropping a reference to another situation where people ascribe religiosity to a reference to god or higher power that could easily be secularized, if preferred, for the sake of personal development.
