Come on, Saint Steven, I've been to a few rodeos before. Universalists are a breed of fanatic that Flat Earthers would envy for their zealotry. I know all the verses that universalists love to pull out of context and fling in my face, blithely ignoring not only the context but the vast number of other verses that are diametrically opposed, not to mention what 99.99% of all Christians have believed and taught for 2000 years. It's the universalists who must do the tap-dancing and explaining away, in spades.
You know as well I do how 1 Corinthians 15:22 is analyzed by mainstream NT scholars.
I'm going to disappoint you by declining to play your game because it's a bottomless rabbit hole of proof-texting nonsense. Believe and promote universalism if you like, but I believe you are doing a disservice to Christianity and skating on very dangerous ice.
You have definitely identified one of the Universal Reconciliation [UR] favorite gotcha verses.
My view is all mankind is inherently "in Adam" because all mankind are literal descendants of Adam.
But all mankind are not inherently "in Christ." That requires a conscious, voluntary action by each person, in this lifetime. No provision for after death.
Our friends over there rather than understanding that the person must be "in Christ" to be made alive, they make the verse say "all will be made alive in Christ." The process of being made alive results in the person being "in Christ."
But that isn't the way the ECF understood it.
Irenaeus Against Heresies. Book V Chap. XII
3.This same, therefore, was what the Lord came to quicken, that as in Adam we do all die, as being of an animal nature, in Christ we may all live, as being spiritual, not laying aside God’s handiwork, but the lusts of the flesh, and receiving the Holy Spirit; as the apostle says in the Epistle to the Colossians: “Mortify, therefore, your members which are upon the earth.”
Tertullian The Five Books Against Marcion. Book V Chap IX
But if we are all so made alive in Christ, as we die in Adam, it follows of necessity that we are made alive in Christ as a bodily substance, since we died in Adam as a bodily substance. The similarity, indeed, is not complete, unless our revival 209 in Christ concur in identity of substance with our mortality210 in Adam.
Tertullian The Five Books Against Marcion VI. On the Resurrection of the Flesh. Chap. XLVIII
For if “as in Adam all die, even so in Christ shall all be made alive,” (1Co_15:22) their vivification in Christ must be in the flesh, since it is in the flesh that arises their death in Adam. “But every man in his own order,” (1Co_15:23) because of course it will be also every man in his own body.