Jesus “knew what was in man” and didn’t mess around with courteous exchanges but immediately drove to the heart of the reason Nicodemus had come.  Jesus recognized that Nicodemus was really seeking after truth and wanted instruction in the way of life, and He was more than willing to give it to him, just as He is today.

Note that Jesus is not impressed by the possibility of making a convert of a member of the Sanhedrin, but treats Nicodemus as He would any other.

“I tell you the truth” is translated as “Verily, verily” in KJV and indicates the importance of what Jesus is about to say. He also gets the undivided attention of Nicodemus with this expression.

Matthew Henry states the following:

Birth is the beginning of life; to be born again, is to begin to live anew, as those who have lived much amiss, or to little purpose. We must have a new nature, new principles, new affections, new aims. By our first birth we were corrupt, shapen in sin; therefore we must be made new creatures. No stronger expression could have been chosen to signify a great and most remarkable change of state and character. We must be entirely different from what we were before, as that which begins to be at any time, is not, and cannot be the same with that which was before. This new birth is from heaven, (#1:13), and its tendency is to heaven. It is a great change made in the heart of a sinner, by the power of the Holy Spirit.

“see” as opposed to entering in and enjoying all of the privileges. The rebirth is absolutely necessary to even begin the kingdom journey.

You cannot “see” the Kingdom of God without being born again. Scripture doesn’t make any sense until we get saved.

Jesus completely wipes out everything Nicodemus has stood for and demands that he recognize how worthless all of his careful observance of the law and traditions of the elders, and his prominence in the religious institutions are and also demands that he forsake all of these things and seek to die to them but receive this new birth from God.  Jesus says that what man needs is not more law but the power of God within him to make him into something brand new.

What we need today is not the truth — we already know it. We don’t need to be told our duty, either, for we also already know that. What we really need is the power to live as we should and enjoy fellowship with a holy God Who desires fellowship with us, and yet cannot look upon our sin. Man has a sin problem and before he will do anything about it, he needs to see how bad sin really is. The power to overcome sin comes only through rebirth into the Kingdom by the blood of Jesus and the power of the Holy Spirit. Jesus has shown us the path to walk and then He made it possible for us to walk it.