Jesus answered and said unto him,
Verily, verily, I say unto you, Except a man be born again, he cannot see the kingdom of God.
Read Chapter 3
Clement Of Alexandria
Mens enim, quae est munda et ab omni vitio libera, est quodammodo apta ad potestatem Dei snscipiendam, cum divina in ea assurgat imago: "Et quicunque habet hanc spem in Domino, seipsum "inquit, "mundum castumque facit, quatenus ille est castus."
In these words he supposes that he can attain complete piety, and imagines that it will be sufficient for his salvation, to marvel merely at those things which call for wonder: nought else but this does he seek. Calling him a Teacher from God, and a co-worker with Him, he does not yet know that He is by Nature God, nor understand the plan of the dispensation with Flesh, but still approaches as to a mere man, and hath but slight conception of Him.
That is, Unless you are born again and receive the right doctrines, you are wandering somewhere outside, and are far from the Kingdom of heaven. But He does not speak so plainly as this. In order to make the saying less hard to bear, He does not plainly direct it at him, but speaks indefinitely, Unless a man be born again: all but saying, both you and any other, who may have such opinions concerning Me, are somewhere outside the Kingdom. Had He not spoken from a desire to establish this, His answer would have been suitable to what had been said. Now the Jews, if these words had been addressed to them, would have derided Him and departed; but Nicodemus shows here also his desire of instruction. And this is why in many places Christ speaks obscurely, because He wishes to rouse His hearers to ask questions, and to render them more attentive. For that which is said plainly often escapes the hearer, but what is obscure renders him more active and zealous. Now what He says, is something lik...
And to these things thou perchance, who art bringing in some novelty, mayest immediately and impatiently reply, as thou art wont, that the Lord said in the Gospel: "Except a man be born again of water and of the Spirit, he cannot enter into the kingdom of heaven."
Accordingly he says more manifestly: "And every (man) who hath this hope in Him maketh himself chaste, just as Himself withal is chaste.".
And accordingly, "he who is being born of God doeth not sin, because the seed of God abideth in him; and he cannot sin, because he hath been born of God. Herein are manifest the sons of God and the sons of the devil."