It is true, those who believe are saved eternally by Christ's death on the cross, but the believing is not what saved them. Christ's death on the cross was over 2000 years ago for those that his Father gave to him (John 6:38) even before they were born into this world and could not have believed. No one believes in God until God gives them the new birth with the indwelling of the Holy Spirit. (1 Cor 2:14).
I agree. This is a different version that speaks that truth plainly. I offer it here so that all may understand even more. The Apostle Saint Paul's Book of 1st Corinthians chapter 2 - The Living Bible Translation
14 But the man who isn’t a Christian can’t understand and can’t accept these thoughts from God, which the Holy Spirit teaches us. They sound foolish to him because only those who have the Holy Spirit within them can understand what the Holy Spirit means. Others just can’t take it in.
And,
15 But the spiritual man has insight into everything, and that bothers and baffles the man of the world, who can’t understand him at all. 16 How could he? For certainly he has never been one to know the Lord’s thoughts, or to discuss them with him, or to move the hands of God by prayer.[
b] But, strange as it seems, we Christians actually do have within us a portion of the very thoughts and mind of Christ.
https://www.biblegateway.com/passage/?search=1+cor+2&version=TLB
Footnote:
1 Corinthians 2:16 to move the hands of God by prayer, or “who can advise him?”