why does Paul say their belief served
NO purpose?
1 Corinthians 15:2 (LEB)
by which you are also being saved, if you hold fast to the message I proclaimed to you, unless you believed to no purpose.
On your view, Paul should have said believed to a temporary purpose or fleeting purpose or conditional purpose or revocable purpose or "everything salvation is now" purpose (which is surely not
no purpose). But he doesn't say that, he says
no purpose or "
vain". This is fact #1 that excludes your interpretation of this passage as being valid.
...
A person in Corinth that holds to a firm belief in a salvific need to continue sacrificing animals (anti-2) or anti-resurrection beliefs (anti-1) or a need to meet a fruit quota (anti-2),
that person had a vain belief in Paul's gospel message to begin with. Which is why the past tense verb is used; "
believed in vain". This is fact #2 about this passage which precludes your interpretation of it.
Romans 11:29 (NASB) For the gifts and the calling of God are irrevocable.
What is vague within this verse?
What the gifts are?
What the calling of God is?
Or what irrevocable means?