There is no suggestion that Paul is addressing the Corinthians as if they were unsaved.
v.12 What we have received is not the spirit of the world, but the Spirit who is from God, so that we may understand what God has freely given us.
The distinction Paul makes between the mature and the unbeliever (whom he 'resolved to know nothing but Him crucified') is very clear. You are shoehorning the unsaved into Paul's discussion of a message for the mature without warrant...
You've read past that again.
Consider the following...
1 Corinthians 2:12 Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God.
In the KJV, both uses of the word "spirit" are in the lower case in that passage with good reason.
Because Paul is contrasting outlooks - the world's outlook, mind, or spirit on a thing, and the Spirit's outlook, mind, or spirit on a thing.
And he is also referring to his mind or spirit having had revealed to it The Spirit's mind, or spirit on a thing by the Spirit.
He is not referring to the Corinthians as Believers, rather; to himself.
Where am I getting this from?
From some supposed "Lord spoke to my spirit...?"
Yes, but only in the sense that He now does so through said Word on things that Paul is asserting there was given to his spirit or mind, to speak or write about.
The Apostles were unique in that.
We are not.
All we have is the Scripture that process in them, resulted in.
Or as Peter put that, near the very end of his God-inspired witness...
2 Peter 1:19 We have also a more sure word of prophecy; whereunto ye do well that ye take heed, as unto a light that shineth in a dark place, until the day dawn, and the day star arise in your hearts: 1:20 Knowing this first, that no prophecy of the scripture is of any private interpretation. 1:21 For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost.
Anyway, all this remains ever fascinating
