What about all the millions who have died since Adam was put on the earth, along with many today who still have never heard of the Gospel? Well, this is what the 'second chance' for 'all' mankind is all about!
Once Adam had transgressed in the Garden of Eden, he and Eve along with all unborn mankind in its imperfection came under the sentence of death. But Almighty God realizing that the real instigator was Satan has decided to give all mankind a second chance to stand once more before him in a state of perfection at the end of the Sabbath Millennium.
God in his loving kindness today, will not judge imperfect man by his own perfect Law; so while at the moment all of us remain 'dead' in God's eyes as Jesus confirmed when he said to one who was about to become one of his 'little flock' "Let the dead bury the dead, you follow me." the provision of Christ's Millennial Rule will enable all during the general earthly resurrection to be brought up to perfection while at the same time understanding what this provision is all about.
At the end of this period, those who this time of their own cognizance, remain faithful to God when Satan who will have been bound for this period, is released for a short period to once more deceive the nations; will therefor receive everlasting life on earth under global paradisaical conditions as first intended. Those who still adamantly follow Satan will along with him perish in the 'second death'! (Revelation 21:
One cannot be in danger of the 'second death' until resurrected from the first death.
So in the end there will be no one on earth who will not have received a full understanding of God's will and purpose.
Alexander