There is a time sometime in the future, when those who are alive, and those have died - even those who have perished in oceans and seas, even all those since mankind was created - will be resurrected and be judged.
Those who have believed will be made immortal and be rewarded with eternal life and glory with God.
“You have no assurance of your life…” - except that which Jesus Christ gives you by His grace, as the result of your belief in Him.
A well-known commentary says it clearly:
“Since everyone who goes before the great white throne is to be tried and sentenced for his deeds, and no one is sinless, the only way to escape condemnation and the “lake of fire” is to have one’s name in the “Book of Life” through authentic faith in Jesus as Lord “ (NASB Commentary)
Will you believe…and find real peace of mind?
“Therefore there is now no condemnation [no guilty verdict, no punishment] for those who are in Christ Jesus [who believe in Him as personal Lord and Savior].” - Romans 8:1 (AMP)