That which is born of the flesh is flesh; and that which is born of the Spirit is spirit. Marvel not

John 3:6-7 (KJV)

That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.

Marvel not that I said unto thee, Ye must be born again.

John 3:12 (KJV)

If I have told you earthly things, and ye believe not, how shall ye believe, if I tell you of heavenly things?