In the NT, there is a wide variety of warning-types against eternal security.
After all, variety is the spice of life!
Please forgive me for only posting one example for each warning-type.
Warnings about being blotted out of the Book of Life
Revelation 3:5 ● “He who overcomes shall be clothed in white garments,
and I will not blot out his name from the Book of Life”
Please note: the “overcomer” of 1 John 5:4-5 only overcomes “the world”,
which is the world of unbelievers in John’s writings!
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Please note that (1 John 5:1) says, "Whosoever believeth that Jesus is the Christ is born of God:...." Then read (1 John 5:4). "For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith."
That faith that resulted in the believer's new-birth is the same faith that overcomes the world. (1 John 5:5) "Who is he that overcometh the world, but he that believeth that Jesus is the Son of God."
And as (Rev. 3:5) says, God "will not blot out his name from the Book of Life."
Stranger