Its a given that scripture says whosever believes hath eternal life Jn 3:16
16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
Jn 3:15
That whosoever believeth in him should not perish, but have eternal life.
And of course this is so true. Yet how does a spiritually dead sinner change from being a unbeliever and hater of God naturally, into a Believer who begins to Love God, the True God ? The answer is by Sovereign Grace, they believe because of Grace Acts 18:27, they also believe because of Election Acts 13:48, even Election is of Grace Rom 11:5-6. A mans believing totally due to Gods Grace 1 Pet 1:21. Hasnt it been said that " No man can come to Jesus except it be given " Jn 6:65
65 And he said, Therefore said I unto you, that no man can come unto me, except it were given unto him of my Father.
The word given didōmi means to bestow as a gift ! This being the case, it goes without saying, nobody can believe in Jesus unless its given to them by Gods Gift of Grace. See Phil 1:29
Everyone who believes in Him shall have eternal life.