Enoch, who walked with God and was taken by him.
Enoch means “dedicated”. Jude points out that he is the “seventh” from Adam. This speaks to the last generation of faithful, dedicated followers, and their rapture.
And Enoch also, the seventh from Adam, prophesied of these, saying, Behold, the Lord cometh with ten thousands of his saints…
Jude 1:14 KJV
The writer of Hebrews notes,
By faith Enoch was translated 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.
What does it take to please God?
And without faith it is impossible to please Him, for he who comes to God must believe that He is and that He is a rewarder of those who seek Him.
The warning is this: it is possible to be a believer, yet unfaithful, undedicated, and thus no “Enoch”:
If we are faithless, He remains faithful, for He cannot deny Himself.
2 Timothy 2:13 NASB
Those who are faithless/unbelieving in the Lord are not translated. They are punished severely. They meet those translated afterwards per #1.