Since Jesus is Light, those who Reject Him go from the Darkness in which they have lived into Gross Darkness where the Holy Spirit will no longer reveal the Light to them.
When a person hardens their Heart toward God is is an overt act of Rebellion. It results in an impenetrable Eternal spiritual state from which there is no Hope of Salvation. This is not to be confused with running from God which many have done and do today.
No one comes to God purely on their own. They are drawn by the Holy Spirit as they Hear the Gospel. Those who Believe and Receive the Gospel are Saved. Those who Reject the Gospel have spurned the Holy Spirit and so are likely to never be bothered by Him again.