IGNORANT AND CANNOT UNDERSTAND
Joh 3:4 Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother’s womb, and be born?
Nicodemus came to Jesus not understanding the way of life. He was religious. He knew the scriptures of the Old Testament and yet did not understand that Jesus was the way of life. Jesus proceeds to inform him of the new birth. Do not wrestle with the fact that the natural man cannot understand those things that are spiritual. Paul enlightens us on this subject.
1Co 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.
Natural man will not understand. It is the work of the Holy Spirit to convict.
Joh 16:7 Nevertheless I tell you the truth; It is expedient for you that I go away: for if I go not away, the Comforter will not come unto you; but if I depart, I will send him unto you.
Joh 16:8 And when he is come, he will reprove the world of sin, and of righteousness, and of judgment:
Joh 16:9 Of sin, because they believe not on me;
When the word is preached, the Holy Spirit convicts.
Rom 10:13 For whosoever shall call upon the name of the Lord shall be saved.
Rom 10:14 How then shall they call on him in whom they have not believed? and how shall they believe in him of whom they have not heard? and how shall they hear without a preacher?
Rom 10:15 And how shall they preach, except they be sent? as it is written, How beautiful are the feet of them that preach the gospel of peace, and bring glad tidings of good things!
Rom 10:16 But they have not all obeyed the gospel. For Esaias saith, Lord, who hath believed our report?
Rom 10:17 So then faith cometh by hearing, and hearing by the word of God.
The preaching of the word brings the conviction of the Holy Spirit. This conviction is making known that there is a God that has sent a Savior. Now Jesus used the natural physical things of this world to compare to spiritual things so there would be understanding. Nicodemus now understood that he must be born again which is the birth from above.