One of the things you'll notice right off, in someone who has experienced the regeneration, or the born again experience, is a clear self-awareness and conviction of one's sinful nature. In fact, Jesus is a light that shines in the darkness; the closer one gets to God the greater one's awareness is of just how unworthy we are of God's love and forgiveness.
This is what the Spirit of God does. He convicts the world of sin. Those who are saved are forever grateful for this new awareness. Those who are lost express bitterness, hatefulness and rage at the very suggestion that forgiveness is needed.
When the Holy Spirit impresses Himself upon a person, all and every inkling of self-worth, self-righteousness and pride withers and hides itself from the Truth.