Tafseer of Surah Al-Kahf (Ayahs 6–9) About Mocking Revelation, Rejecting Truth

Why do people mock revelation, reject the Messenger, and turn away from what is clearly true? 
In this continuation of the Tafseer of Surah Al-Kahf, ayahs 6–9, the discussion uncovers the fierce reality of denial, arrogance, and the refusal to reflect on the signs in the heavens and the earth.