Mark 9:42-50
42 And whosoever shall offend one of these little ones that believe in me, it is better for him that a millstone were hanged about his neck, and he were cast into the sea.
43 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:
44 Where their worm dieth not, and the fire is not quenched.
45 And if thy foot offend thee, cut it off: it is better for thee to enter halt into life, than having two feet to be cast into hell, into the fire that never shall be quenched:
46 Where their worm dieth not, and the fire is not quenched.
47 And if thine eye offend thee, pluck it out: it is better for thee to enter into the kingdom of God with one eye, than having two eyes to be cast into hell fire:
48 Where their worm dieth not, and the fire is not quenched.
49 For every one shall be salted with fire, and every sacrifice shall be salted with salt.
50 Salt is good: but if the salt have lost his saltness, wherewith will ye season it? Have salt in yourselves, and have peace one with another.
First vs. 42 begins with a warning of a fate worse than death so it hardly follows that in vs. 49 Jesus is saying all mankind will be saved, righteous and unrighteous alike, even after death.
Then Jesus describes a place where the fire is not quenched and the worm of each person in that place never dies.
Then Jesus states "every one shall be salted with fire, and every sacrifice shall be salted with salt." What does that mean?
Ezekiel 43:23-24
23 When thou hast made an end of cleansing
it, thou shalt offer a young bullock without blemish, and a ram out of the flock without blemish.
24 And thou shalt offer them before the LORD, and the priests shall cast salt upon them, and they shall offer them up
for a burnt offering unto the LORD.
Leviticus 2:13
13 And every oblation of thy meat offering shalt thou season with salt; neither shalt thou suffer the salt of the covenant of thy God to be lacking from thy meat offering: with all thine offerings thou shalt offer salt.
Every offering must be without blemish before they are salted, they are not made "without blemish" by the fire/salt.
So vs. 49 refers only to followers of Jesus not all mankind.