Jesus was a lot less shy about preaching the reality of Hell than modern Christians often are. Whereas we rarely preach about Hell, and many of us are even scared to mention the word, Jesus emphasised the horrible details none of us ever want to experience first hand.
Jesus was so vehement in His desire to convince us not to go there that He actually said it is better to lose one's hands, feet, or eyes than to go there, following each statement up with "where their worm does not die, and the fire is not quenched".
There is much debate over what, exactly, this refers to. Is Hell literally a place of fire? What is this worm that never dies? It is my view that such disputes are fruitless. Regardless of whether or not the fire and worms are literal, Jesus saw fit to warn us that if we do not repent and believe, an eternity of punishment awaits us, and that punishment is so unbearable, it's better to encounter serious bodily harm than to go there.
So why do we water it down? Why do we preach so much about Heaven, but act as if Hell is just a side note? Why do we pretend Hell has an expiration date? Why do we put so much effort into allegorising the fire? For what? Feelings? God forbid we should offend our unbelieving friends by warning them of an eternal fate so terrible, it's better to lose an eye! Apparently, it's better to let them walk into that fire in ignorance than try to talk them out of it with fear and trembling.
There's a saying I heard once: "I'd rather offend you into Heaven than flatter you into Hell." Do not let a single unbeliever perish with your consent. It is sheer negligence to deny, or ignore the reality of Hell just for the sake of not offending people.