I find this idea to be beyond belief and without any credibility.
John 3:36 - whoever believes in the Son
has eternal life.
John 5:24 - whoever hears my word .....
has eternal life.
John 6:47 - the one who believes
has eternal life.
John 6:54 - whoever eats my flesh
has eternal life.
John 17:3 - this is eternal life; that they know you.
Romans 6:23 - the gift of God is eternal life.
1 Timothy 6:12 - take hold of the eternal life which you
received .......
Jesus came to give life in all its fulness. He did not say, "just muddle along in this life, for now and you will have fulness of life when you die."
(And no, that does not mean I believe the Prosperity Gospel.)
The time when all those worthy will obtain immortality, is after the Millennium. Revelation 20:15-21
We are only worthy through Jesus - who makes us righteous, 2 Corinthians 5:21.
However; your belief of now for Eternal life, is not a bad thing, just keep in mind it cannot be a reality yet.
So Christians don't have any assurance or security?
We shouldn't sing the hymn, "Blessed assurance, Jesus is mine", but "let's hope, one day, we will have eternal life"?
What did John write? "I am writing to you who believe in the Son of God, so that you may
know that you have eternal life", 1 John 5:13.
The problem with it, is the confusion and mistaken ideas of our role in the coming Kingdom.
The Kingdom is already here - though not fully.
It started when King Jesus came to earth. It is found wherever Christians honour and accept Jesus as king, are telling others about him and are doing the work that he has called us to. It will be seen in all its fulness when King Jesus returns in glory.