Not all Christian denominations will agree with the following, but this is generally what is believed by those that accept the Bible as literal truth (except where it is obviously meant to be allegorical, hyperbolic, etc.).
The first general resurrection occurs at Christ's return.
It is for those (a relatively small number) that have been saved, "the elect", whether dead or still alive:
It is a spiritual resurrection to immortality, not a physical resurrection.
Jesus answered, “Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God.
That which is born of the flesh is flesh, and that which is born of the Spirit is spirit.
Do not marvel that I said to you, ‘You must be born again.’
The wind blows where it wishes, and you hear the sound of it, but cannot tell where it comes from and where it goes. So is everyone who is born of the Spirit.”
1 Corinthians 15:51–52:
Behold, I tell you a mystery: We shall not all sleep, but we shall all be changed —
in a moment, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, and the dead will be raised incorruptible, and we shall be changed.
1 Thessalonians 4:16–18:
For this we say to you by the word of the Lord, that we who are alive and remain until the coming of the Lord will by no means precede those who are asleep.
For the Lord Himself will descend from heaven with a shout, with the voice of an archangel, and with the trumpet of God. And the dead in Christ will rise first.
Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air. And thus we shall always be with the Lord.
And I saw thrones, and they sat on them, and judgment was committed to them. Then I saw the souls of those who had been beheaded for their witness to Jesus and for the word of God, who had not worshiped the beast or his image, and had not received his mark on their foreheads or on their hands. And they lived and reigned with Christ for a thousand years.
But the rest of the dead did not live again until the thousand years were finished. This is the first resurrection.
Blessed and holy is he who has part in the first resurrection. Over such the second death has no power, but they shall be priests of God and of Christ, and shall reign with Him a thousand years.
The second resurrection occurs at the end of the Millennium.
This is when all those that have died without an opportunity to be saved will be resurrected, still as physical mortals.
They will have their first opportunity at salvation, living in the wonderful world that the Earth has become during the Millennium, being taught by the resurrected saints.
Then comes the final judgement.
The small number of people that knowingly rejected God's salvation will be burned to ashes, permanently destroyed.
(Some think that this requires a third resurrection for these people.)
And I saw the dead, small and great, standing before God, and books were opened. And another book was opened, which is the Book of Life. And the dead were judged according to their works, by the things which were written in the books.
The sea gave up the dead who were in it, and Death and Hades delivered up the dead who were in them. And they were judged, each one according to his works.
Then Death and Hades were cast into the lake of fire. This is the second death.
And anyone not found written in the Book of Life was cast into the lake of fire.
You shall trample the wicked, For they shall be ashes under the soles of your feet …
“Therefore I say to you, every sin and blasphemy will be forgiven men, but the blasphemy against the Spirit will not be forgiven men.
Anyone who speaks a word against the Son of Man, it will be forgiven him; but whoever speaks against the Holy Spirit, it will not be forgiven him, either in this age or in the age to come.