Where do you look at Truth from? From below, where what there is, is only what can be seen, tested, and verified? If you look from this perspective you won’t be able to see miracles, the supernatural, or any of God’s works. This is the reason why Nicodemus doesn’t understand the words of Christ; he’s thinking with a perspective "from below". The kingdom of God, however, is something received "from above" rather than earned from below. God creates man anew with a right spirit from above so that with his spirit he might receive the gifts of God eternally into new life.
Scripture: John 3:1-17