Its not having to do with becoming regenerate...
The natural man (the soulish man - psukikos) will not be able to comprehend Bible doctrine which has been designated for believers who have entered into regeneration..
But, no one is required to understand the Deity of the Jesus to become saved. The natural man would see that teaching as foolishness.
The salvation message is designed to reach a man on the level of him being flesh.
For any unbeliever can know he is a sinner.
But, the unbeliever can not understand the Deity of Christ!
Regeneration does not require knowing anything that any unregenerate person can not grasp.
The unbeliever can know he is a sinner, and that a man named Jesus Christ died on a cross for his sins!
That's all that's needed to enter into regeneration.
After regeneration? Then that man stops having the limitation he had before he was saved, and now can begin to comprehend such things that the natural man found to be foolishness.
Even the reprobate unregenerate Pharaoh could know he was a sinner!
Then Pharaoh summoned Moses and Aaron.
“This time I have sinned,” he said to them. “The LORD is in the right,
and I and my people are in the wrong."
Exodus 9:27
Pharaoh knew what was needed to become saved! To become regenerate!
grace and peace .............