Jesus spoke to everyone. Believers and non-believers. He spoke of hell BEFORE He was crucified. He spoke of the horrors of hell and the wonders of Heaven.
Cdm, Jesus did die and all of our sins were forgiven as soon as we accepted Christ as the Savior and acknowledged that He did die for us and for our sins to be wiped clean.
Also, cdm, please know that if you were the only person alive at that time, Jesus would have still died for you.
Thank you. Hinduism also speaks of hell as the greatest horror.