Romans 8:1 “There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit.”
Round and round we go.
How are we to define “them which are in Christ Jesus?”
This is the problem or one of them, in my view. First a set of choices is presented as though they were exhaustive. EITHER ALL the saved know they're saved, or NONE do. (Why shouldn't God let some know and others not know depending on His idea of how each individual might best proclaim the Gospel.)
Then it's presented that unless one has "assurance" one has no Gospel. Maybe some of us are too caught up with where we are right NOW with God that we just aren't worrying about assurance or not.
Then there is a tacit equivalence between "there is no no condemnation" and "they KNOW they are not condemned."
Any of the propositions might be true. But NONE of the arguments brought up to show their truth can do the job.
At least that's how it looks from here. I'd certainly consider an argument. I just don't think one has been offered.