If your religion teaches resurrection of the dead on the Judgement Day, and you believe all dead people will be resurrected, here is a case:
Suppose somebody was eaten by a shark in the sea. The man's body absorbed by shark, and later once the shark dies, its body eaten by other fishes, and some of those fishes were eaten by some fishers.
On the Judegme Day, this man has no specific grave. So, where does he come out? Where does he get resurrected?
The grave can be either literal or metaphoric like death itself. When the Bible speaks of death, it can be physical death or spiritual death. One means cut off from life...the other means being cut off from God. Both have the same basic meaning...a dead person ceases to exist.
The grave can be an individual resting place for a dead body, or a figurative receptacle for all the dead...sheol was "the abode of the dead"....a place where all dead people go because that is what a grave is for.....a place for the dead to go to "rest in peace". (Ecclesiastes 9:5, 10)
God does not need a single molecule of any person to resurrect them. It is a recreation, or regeneration of one's body and a reinstalling of all memories so that the person can not only self identify but others can also identify them.
Judgment day is not a single event. The final judgment of this world is a single event, but Judgement day is actually "the last day" or the last period of the 1,000 years reign of Christ. Its the one that Lazarus' sister spoke of before Jesus raised her brother. (John ch 11) She knew about "the resurrection on the last day".
When Jesus promised a resurrection to 'both the righteous and the unrighteous', he said that the unrighteous would enter a period of judgment. These are not the incorrigibly wicked (whom Jesus consigned to "gehenna"...."the lake of fire", which is "the second death" ...this is a death from which there is no resurrection. Only God knows who is in this place. They will never come out.) Unrighteous does not mean wicked.
In where recreate them? That is the question. If they had a grave, they say, they just come out of grave. If eaten by animals, there is no grave. So, where they become resurrected?
There are two resurrections spoken about in the Bible....a "first resurrection" for those chosen for rulership positions with Christ in heaven, (Revelation 20:6) and a second 'general' resurrection of the dead after his kingdom is established on earth. Both are performed by Jesus Christ. (John 5:28-29) So whether he calls the dead from literal graves or figurative ones, the result is the same......but the destinations for both are different. Those resurrected "first" are given a new spiritual body in order to join Christ in heaven, and those resurrected as their subjects on earth are given new physical bodies, so as to resume life and relationships here on earth.
When Jesus performed resurrections back in the first century, his delight was to be able to return these ones to their families. We can just imagine the joy when families separated by death are reunited.....to everlasting life on earth....which is what God purposed in the beginning....