That is, it is not possible to enter heaven unless one is born again. There are no exceptions to this rule. A Universal, Moral and Mental Necessity Regeneration is a universal necessity. All whose hope is salvation must be born again. That is, our Lord was not speaking to Nicodemus only, but to all who are in the same spiritual condition as Nicodemus.
Regeneration is a moral necessity.
The reason men are immoral is because they are separated from the life of God, which life is one of righteousness and holiness. In the New Birth, the Spirit of God changes an individual by taking up residence. Because of the indwelling of the Spirit, one is drawn toward holiness, righteousness and right conduct. Regeneration is a mental necessity. He that is dead in sin is dead toward God.