I don't understand this sentiment at all. Identifying positive aspects in existing religions is perfectly fine (I'd even argue there is some amount of virtue to it). How is it possibly ghoulish to see good in other cultures/religions and bring that into your practice? One example that comes to mind are religions where consumption of meat is eschewed. If you find that the rationale that Jainism provides for a vegan lifestyle resonates with you, why can't you incorporate that into your life for those reasons?

Again though, and I think this is enough information to understand my position, I simply reject the notion that you can build anything worthwhile by picking and choosing bits you like from the collection of religions spread before you.

They are traditions whose fullness is only experienced as part of a community of other practitioners. By trying to extract an appealing bit and apply it to your own life outside of that context and separated from that practice, you're doing an entirely different thing and imo not what you think you're doing. I simply don't think this practice is worthwhile, valuable, or worthy of respect.

If you don't want to eat meat then don't eat meat. If a jain convinces you not to then that's as good a way to find out as any other. Does that begin to convince you that we are all part of an eternal cycle made up of different substances? Maybe you should convert to jainism!

I don't want to assume anything about you and I'm not really. But I often see this amalgamated spirituality concept coming from non-religious people. The idea that you can take the parts you like from anywhere, leaving the parts you disagree with. I simply don't think you can come out of this with anything meaningful, and in fact I think it's a trap. You'll think you've found wisdom when all you're doing is laundering your beliefs & preferences through the hard-won ancient traditions of the world.

There is courage necessary to commit to a path without possibly being able to understand it or even begin to know where it will lead. When you build your own religion you trade that in for mistaken confidence, and the feeling that you know what all the parts do and why they're there. You're not supposed to know why they're there! You're supposed to just live it.

It is certainly true that feeding at the buffet of world religions isn't the same as being a committed member of a particular religious community. But that doesn't mean that you don't get some value from it, and potentially different value than that found by the more committed members.

I personally take great inspiration from Hesse's Siddhartha, the titular character of which explores a variety of spiritual and religious traditions, finds them all lacking and ends up being most inpired by a river ferry man. But that doesn't mean that the character gained nothing from his experiences with Buddhism, Jainism, ascetism and more.

It is not picking through or over the bones of Quakerism to grapple with and/or be inspired by this idea.

As for Stoicism, I am not sure that it is required to do anything other than, maybe, bring greater peace and understanding into the lives of those considering its values.

no no no no no. some progressive protestant faiths perhaps, but the central tenet of most Christian and most Protestants faiths is faith, salvation comes through accepting Jesus Christ as your savior and repenting sin, for which you will be forgiven. It is a topic of debate among theologians as to what that says about works/acts but they don't generally depart from the idea that starting now you get a clean a slate, or as clean as anyone can.