And as it is appointed unto men once to die, but after this the judgment:
— Hebrews 9:27 —

The Book of Enoch
I used to have a copy of The Book of Enoch. After reading it, I realized why it isn't in the Bible. It isn't Bible. If The Book of Enoch was really written by Enoch, it would be the oldest book in the world. Noah would have brought it with him on the ark. The Book of Enoch is a Gnostic book written much later. That is why the Freemasons and New Agers have a high opinion of it. Too many people are using The Book of Enoch to interpret their Bibles, instead of using their Bibles to discern that The Book of Enoch isn't Bible. The Book of Enoch is more akin to the Babylonian "Talmud" that the Jews love so much. Why do you suppose they want to convince you to trust The Book of Enoch?
The whole thing about Enoch going to heaven, witnessing all these things, and then coming back to tell about it is fantasy, like "Dante's Inferno." All we need to discern that The Book of Enoch isn't Bible, nor was it written by Enoch, is that Enoch never went to heaven. The Bible doesn't even say he did. But The Book of Enoch is highly regarded among Freemasons, New Agers, Kabbalists, and Satanists.
Genesis 5:24 And Enoch walked with God: and he was not; for God took him.
Enoch and Elijah are often sited as examples of people who have gone to heaven, but is that what the bible says? The apostle Paul included Enoch in his list of people of faith from the old testament.
Hebrews 11:5 By faith Enoch was translated [metatithemi] that he should not see death; and was not found, because God had translated him: for before his translation he had this testimony, that he pleased God.
"Enoch was translated that he should not see death." What does it mean to be translated?
Colossians 1:12-14 Giving thanks unto the Father, which hath made us meet to be partakers of the inheritance of the saints in light: 13Who hath delivered us from the power of darkness, and hath translated [metatithemi] us into the kingdom of his dear Son: 14In whom we have redemption through his blood, even the forgiveness of sins:
"Enoch was translated that he should not see death." Did Enoch die?
Hebrews 11:13 These all died in faith, not having received the promises, but having seen them afar off [future], and were persuaded of them, and embraced them, and confessed that they were strangers and pilgrims on the earth.
Taken in context, the same scripture that tells us Enoch was translated also tells us he died, as did everyone in Paul's list. So what death is it that Enoch "should not see?"
Revelation 20:6 Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power,...
Hebrews 9:27 ...as it is appointed unto men once to die, but after this the judgment:
John 3:13 And no man hath ascended up to heaven, but he that came down from heaven, even the Son of man which is in heaven.
No exceptions!
What about Elijah?
II Kings 2:1 And it came to pass, when the LORD would take up Elijah into heaven by a whirlwind, that Elijah went with Elisha from Gilgal.
II Kings 2:11 And it came to pass, as they still went on, and talked, that, behold, there appeared a chariot of fire, and horses of fire, and parted them both asunder; and Elijah went up by a whirlwind into heaven.
A chariot and horses of fire came between Elijah and Elisha to separate them, and then a whirlwind swept Elijah away into heaven. Which heaven? The bible speaks of three heavens. The first being the earth's atmosphere, the daytime heaven. The second heaven is the universe that we see at night, and the third is the spiritual heaven. In which heaven do whirlwinds (tornadoes) appear? What became of Elijah?
II Kings 2:16 And they said unto him, Behold now, there be with thy servants fifty strong men; let them go, we pray thee, and seek thy master: lest peradventure the Spirit of the LORD hath taken him up, and cast him upon some mountain, or into some valley. And he said, Ye shall not send.
John 3:12-13 If I have told you earthly things, and ye believe not, how shall ye believe, if I tell you of heavenly things? 13And no man hath ascended up to heaven, but he that came down from heaven, even the Son of man which is from heaven.
Hebrews 11:39 And these all, having obtained a good report through faith, received not the promise: God having provided some better thing for us, that they without us should not be made perfect.
They must wait to be resurrected with us. As for the appearance of Moses and Elijah with Jesus on the "mount of transfiguration," I only offer this.
Matthew 17:9 And as they came down from the mountain, Jesus charged them, saying, Tell the vision to no man, until the Son of man be risen again from the dead.