Matthew 13:42: "And shall cast them into a furnace of fire: there shall be wailing and gnashing of teeth."
Matt 25:41: "Then shall he say also unto them on the left hand, Depart from me, ye cursed, into everlasting fire, prepared for the devil and his angels." This passage relates to Jesus' judgement of all the world. It describes precisely how Jesus will separate the "sheep" -- those who will spend eternity with God in Heaven -- and the "goats" -- those who will be tortured for all eternity in Hell. The criteria was based on the good works (or lack thereof) of people while they lived on earth. This conflicts with many references in the Christian Scriptures which specify that salvation depends upon one's beliefs, not good works.
Mark 9:43-48: And if thy hand offend thee, cut it off: it is better for thee to enter into life maimed, than having two hands to go into hell, into the fire that never shall be quenched." The reference to fire is repeated three more times in the passage for emphasis.
Luke 16:24: "And he cried and said, Father Abraham, have mercy on me, and send Lazarus, that he may dip the tip of his finger in water, and cool my tongue; for I am tormented in this flame." This is a plea described as coming from an inhabitant of Hell.
Revelation 20:13-15: "...hell delivered up the dead which were in them...And death and hell were cast into the lake of fire. This is the second death. And whosoever was not found written in the book of life was cast into the lake of fire."
Revelation 21:8: "But the fearful, and unbelieving ... shall have their part in the lake which burneth with fire and brimstone." Brimstone is sulphur. In order for sulphur to form a lake, it must be molten. Thus, its temperature must be at or above 444.6 °C or 832 °F. That is the boiling point of sulfur.