The bible even in in its translated form, is still absolutely clear that it is a singular event of belief in the completed work of Christ Jesus that brings eternal life and eternal life is eternal
and there is not any possible way to logically argue that eternal life is temporal unless one wants to call God a liar
Having said that perhaps a little research into the Greek will help.....
TEXT 1 John 5:1 Whosoever believeth that Jesus is the Christ is born of God: and every one that loveth
him that begat loveth him also that is begotten of him.
KOINE Πᾶς ὁ πιστεύων ὅτι Ἰησοῦς ἐστιν ὁ Χριστὸς,
ἐκ τοῦ Θεοῦ γεγέννηται καὶ πᾶς ὁ ἀγαπῶν τὸν
γεννήσαντα, ἀγαπᾷ καὶ τὸν γεγεννημένον ἐξ αὐτοῦ.
KEV 1 John 5:1a Everyone who is believing that Jesus is the Christ, has been previously generated (and remains generated) out from the God…
The word
γεγέννηται is perhaps the most important term in soteriology; for it speaks of the act of God to “generate” one from above. John is writing to provide “divine insight” for those actually born from above, in order that they might “notice” that “they” are having eternal life.
The word is in the perfect tense, which means that as (Davis, 1923) states “[it]
expresses the continuance of completed action. It is then a combination of punctiliar action and durative action:
This kind of action expressed by the perfect tense is sometimes called perfective action” (p. 152).
The word γεγέννηται as a perfect tense describes for the child of God that the kind of birth experienced out from the
God is a “perfect birth,” that is, a birth that is completed in the past with present, continuing results. The New Birth is a perfect birth. Thusly, the child of God is one who is generated out from the God and
remains generated out from the God; further, the child of God is one who (
because of his birth out from the God) is continuously believing
http://www.iamkoine.org/uploads/3/4/5/9/34593438/the_case_for_koine_final.pdf
All of these are absolutely true FOR THE ONE WHO CONTINUES TO BELIEVE. They have zero application to the one who has stopped trusting in the blood of Christ. The promises belong to those who continue to believe. That's why we are exhorted and warned to keep believing what we first heard and believed.
The problem is not a matter of denial or rejection so much as is it is a problem of reading the promises of God out and away from the context of the whole counsel of God, which shows us that the sure promises are only sure
for the one who continues to believe.
And here's a perfect example. You left off the last part of 1 Peter 1:5. You left off the 'through faith' part. We are kept by God's power for the day of salvation
THROUGH FAITH.
"5who are protected by the power of God through faith for a salvation ready to be revealed in the last time." (1 Peter 1:5 NASB)
There is no argument or debate possible about the necessity to keep believing in order to be saved because the Bible is clear about that. The only real question is, "can a true believer stop believing?" But consider that even Paul warns us to not be arrogant, but rather fear in regard to continuing in the kindness of God:
"19 You will say then, “Branches were broken off so that I might be grafted in.”20 Quite right, they were broken off for their unbelief, but you stand by your faith. Do not be conceited, but fear; 21 for if God did not spare the natural branches, He will not spare you, either. 22Behold then the kindness and severity of God; to those who fell, severity, but to you, God’s kindness, if you continue in His kindness; otherwise you also will be cut off." (Romans 11:19-22 NASB)
So apparently Paul thought it quite possible that we could stop trusting and clinging to God's kindness in salvation.