The Hard Hearted
"But after thy hardness and impenitent heart treasurest up unto thyself wrath against the day of wrath and revelation of the righteous judgment of God" (Romans 2:5).
Hard hearts always reject Jesus Christ, and will go on rejecting Him until their hearts are made tender to the Word. Those who are saved later in life have harder hearts than those who are younger. That's why children can be saved more easily than adults. In fact, Jesus even said that adults can only be saved by possessing the same tenderness as children. "Verily I say unto you, Whosoever shall not receive the kingdom of God as a little child, he shall not enter therein" (Mark 10:15).
No one can reverse the effects of a hard heart without God's Law threatening them with judgment. The hammer of God's Law breaks our heard hearts, making it tender to receiving the Savior, but continual obedience to the Word of God keeps it that way. Proverbs 4:23 says that you should make the diligent caring of your heart life's top priority. "Keep thy heart with all diligence; for out of it are the issues of life."
Notice the word "issues." What comes out of the heart is the same character as the heart. If the heart is hard, everything coming out of it is also hard. The Bible talks about many hard issues coming out of hard hearts. Hard hearts have hard wills; hard hearts have hard attitudes; hard hearts speak hard words; hard hearts make hard demands; hard hearts love hard living and suffer hard consequences. The ungodly waste their hearts with hardness, but the godly preserve their hearts with tenderness.