As I've pointed out before, people refuse to listen to God. They do so because they don't want to obey the Lord. God spoke in Jeremiah 32:33 (KJV) "And they have turned unto me the back, and not the face: though I taught them, rising up early and teaching them, yet they have not hearkened to receive instruction."
The Lord clearly wants to teach us but some don't want to learn. Scripture calls them fools. Psalm 53:1 (KJV) reads, "To the chief Musician upon Mahalath, Maschil, A Psalm of David. The fool hath said in his heart, 'There is no God.' Corrupt are they, and have done abominable iniquity: there is none that doeth good."
In fact, it's human stubbornness which makes people reject God and his wisdom. Look at what Proverbs 1:7 (KJV)says. "The fear of the LORD is the beginning of knowledge: but fools despise wisdom and instruction."
But what happens to those who reject God in this life? They damage themselves with their folly. Job 5:2 (KJV) reads, "For wrath killeth the foolish man, and envy slayeth the silly one." A search for words like "fool" and "foolish" brings up many verses regarding the dichotomy between the unwise and the wise. Foolishness is always related to rejecting God in the Bible.
Since this is so, we need not fret when people reject the gospel that we preach. God has given humanity the astonishing privilege of accepting or rejecting his reign. It's for this reason that I'm writing a book called You Think You're Going to Heaven? I hope to change people's minds, through the power of the Holy Spirit, so that they may be saved from an agonizing eternity apart from God.