This statement specifically was given by John to repudiate the belief of many Jews at the time that they were saved from God's wrath simply because they were children of Abraham. This same attitude can be found today also. Many think that they are born of God because they live in a Christian nation, or because their parents are Christians. None of his own works or beliefs can bring about the new birth. It is not men who decide how a man can be saved, but God.
Many people think that they can decide what saves a man.
They come up with their own ideas about who gets saved. God has provided two ways of salvation for men. Unfortunately, noone in the fallen human race is able to perfectly follow God's law. The other way that God has provided is through His Son, Jesus Christ, who was sacrificed on our behalf, to pay for our sins. It is through belief in this work of Christ that we are saved.