John 3:3 referrs to Nicodemus, a ruler of the Jews then.He was a pharisee and by ranking a ,'bishop' of his days.Jesus was amazed ,that he could not understand the difference between heart and spirit of man and flesh of man.What then was he the teacher, teaching to the people?Saint Dominic like all the orthodox saints are cannonized after a series of evaluations by the people at helm of affairs in the church.God alone can tell who is truly born again and those who are not.we can also guess as human beings judging by the good works or otherwise of the persons under consideration.The sainthood is entirely under the rules of cannonization of the church in question, so the platforms are not the same.A saints opinion is purely personal to him while the scriptures and teachings of Jesus remain as they are.Try to seperate the two and you will surely gain a greater understanding.Remember ,the words that i speak to you they are spirit and life' said Jesus christ.Saint Dominic may have his own opinion as what being born again means today like most ordained rev,fathers yet they are purely personal.