I am kind of alone in this understanding but as I read it, for the author of 1 John the KOSMOS is temple-centric Judaism. I believe his reference to the passing away of the world (KOSMOS) is a reference to 70AD. John wrote:
[1Jo 2:15-18 CSB] 15 Do not love the world or the things in the world. If anyone loves the world, the love of the Father is not in him. 16 For everything in the world -- the lust of the flesh, the lust of the eyes, and the pride in one's possessions -- is not from the Father, but is from the world. 17 And the world with its lust is passing away, but the one who does the will of God remains forever. 18 Children, it is the last hour. And as you have heard that antichrist is coming, even now many antichrists have come. By this we know that it is the last hour.
So he says repeatedly that it is the final hour and he says the world is passing away. The only KOSMOS that passed away in 70AD was the then contemporary theocracy. They were the "heavens and the earth" mentioned here:
[Isa 66:22 CSB] 22 "For just as the new heavens and the new earth, which I will make, will remain before me" -- this is the LORD's declaration -- "so your offspring and your name will remain.
Paul also speaks of a "new creation":
[2Co 5:17 KJV] 17 Therefore if any man [be] in Christ, [he is] a new creature: old things are passed away; behold, all things are become new.
[Gal 6:15 KJV] 15 For in Christ Jesus neither circumcision availeth any thing, nor uncircumcision, but a new creature.
I've long understood the KOSMOS as referring to Israel but never felt like understood how John got to that usage. It recently dawned on me that it is from somewhat obscure reference:
Gen 35:11 NASB - God also said to him, "I am God Almighty; Be fruitful and multiply; A nation and a company of nations shall come from you, And kings shall come forth from you.
This "company of nations" of course refers to the various tribal-nations that constitute "Israel"; IE: Israel and Judah, the northern and southern kingdoms. That is "array" or "arrangement" is what John is referring to.