Natural man cannot welcome the things of God.1cor2:14
He cannot, unless given a new heart at regeneration.
In that context, God is not making a contrast between the 'regenerate" versus the "unregenerate" but is contrasting man's understanding verses God's understanding.
1 Corinthians 2:11 you do not know what is in my mind unless I reveal it to you. Nor do I know what is in your mind unless you tell me. You nor I know what is in the mind of God unless He reveals it to us.
And God did reveal His mind to us in that God selected certain men ("spiritual men") and miraculously endowed them with inspiration so those men could receive "
words" (1 Corinthians 2:13) from the Holy Spirit, those inspired men were taught "words". Those inspired, spiritual men, as Paul, wrote those revealed, inspired words down so the natural man can read and understand them, Ephesians 3:3-4.
1 Corinthians 2:14 "
But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned."
From the context we know that the natural man:
1) has no Divine, supernatural inspiration from the Holy Spirit to access the mind of God as the inspired writers did (spiritual men).
2) the natural man's knowledge is therefore limited to things of the world/wisdom of man
So the natural man here would be as those Greek philosophers, they had no Divine inspiration and their knowledge was limited to things of the world/wisdom of man.
Therefore when they hear the gospel, they judge it to be foolishness for they are judging it according to the wisdom of world/men.
Two points:
1) for them to judge the things of God as "
foolishness" implies they had to first understand it to then pass judgment upon it. Therefore they are
NOT totally depraved to the point to where they cannot understand it, but instead they
DO UNDERSTAND it and since they are limited to wisdom of men, it therefore is judged as "
foolishness" to them. Stephens' lost "unregenerate" audience in Acts 7 did not kill Stephen because they did not understand what he preached. But instead they killed Stephen for they
DID understand what he preached, hated what he preached therefore killed him.
2) to know the mind/things of God requires willingness on the part of man (John 7:17). Studying and searching of God's word to learn it and have knowledge of it is required. These natural men, as those Greek philosophers, are not willing - they are not going to take the time to search and study God's word in order for them to know it (spiritually discern it). So the natural man in the context is the man unwilling to know the mind of God by studying God's word.
Therefore 'regeneration' is not some miraculous act required by God to perform upon men to 'enable' men to understand, believe His word. If such were the case, then how does God determine whom He will or will not "regenerate"? God would then become a 'respecter of persons' in "regenerating" one man but not another.
But regeneration takes place when one of his own will choose to submit to water baptism THEN one walks in newness of life, Romans 6:1-6