“Here, then, is the character or nature of the new birth. It is not the reformation of the outward man, it is not the education of the natural man, it is not the purification of the old man, but it is the creation of a new man.
It is a Divine begetting ( James 1:18). It is a birth of the Spirit ( John 3:6). It is a being made a new creation ( 2 Corinthians 5:17). It is becoming a partaker of the Divine nature ( 2 Peter 1:4). It is a being born into God’s family. Every born again person has, therefore, two natures within him. One is sinful, the other is spiritual.
These two natures are contrary the one to the other ( Galatians 5:17), and in consequence, there is an unceasing warfare going on within the Christian.
It is only the grace of God which can subdue the old nature; and it is only the Word of God which can feed the new nature.”
~ Arthur Pink, “Exposition of the Gospel of John”