something. What’s a something?
Well, what’s a “thing”? Etymology matter because this -ism originates NOT in English speaking but Dutch.
“From Middle English thing, from Old English þing, from Proto-Germanic *þingą; compare West Frisian ding, Low German Ding, Dutch ding, German Ding, Swedish, Danish and Norwegian ting.”
The word originally meant “assembly”, then came to mean a specific issue discussed at such an assembly, and ultimately came to mean most broadly “an object”.
So, you want an entity because English has it narrowed to that.
But I strongly strongly suspect the usage of “assembly” has remained in Dutch.:
A “thing” is an issue up for discussion at an assembly.
In short, perfect for a faith in a something. Up for discussion.
But if you insist on a singular, it’s “reality”. That’s the something-other.
English does not have a direct word for iets but it’s a cognate for “aught” or “ought”. From that you can get a sense of the “positiveness” of the something (as in, “there must be something”) which is why it resists elimination.