And if your eye causes you to sin, pluck it out and throw it away. It is better for you to enter into life with one eye than having two eyes to be thrown into the fire of hell.
— Matthew 18:9
Jesus took hell very seriously. He spoke about it as a real place to avoid at all costs.
The most awful thing imaginable would be to die and go into eternity without Christ; to stand before the judgment bar of Almighty God, who knows your every thought and word and deed, and to have all of your sins brought out before the universe and be justly condemned unto eternal perdition and cast out into a lake of fire.
There are some people who have tried every conceivable way to deny the reality of impending judgment for unrepentant sinners. This ranges from denying that there is a God who could possibly punish them; to denying that there is a Hell where they could be punished; to denying that a loving God would ever send anyone there (even such a reprobate as themselves); to claiming that God must, at least, give everyone the opportunity to hear the Gospel.
Not that this would help them, because they have been doing what people constantly try to do, which is to justify themselves by condemning God and end up proving that God is unjust and unfair and unloving, and they themselves must be, by comparison, pretty decent sort of folks.
Since Jesus took hell so seriously, so should we.