Because the first resurrection is to the dead in Christ.
No, according to scripture, the first resurrection was Christ's resurrection.
Acts 26:23 That
Christ should suffer, and that he should be the first that should rise from the dead, and should shew light unto the people, and to the Gentiles.
1 Corinthians 15:20 But
now is Christ risen from the dead, and become the firstfruits of them that slept. 21 For since by man came death, by man came also the resurrection of the dead. 22 For as in Adam all die, even so in Christ shall all be made alive. 23 But
every man in his own order: Christ the firstfruits; afterward they that are Christ's at his coming.
Next in order after the first resurrection (Christ's resurrection) are "they that are Christ's at his coming". A first resurrection implies a second resurrection. The order Paul gave was Paul's first and then next in order is "they that are Christ's at his coming", which makes that resurrection the second resurrection, not the first.
Having part in the first resurrection, which results in the second death no longer having power over you (Revelation 20:6), is to spiritually have part in Christ's resurrection as passages like the following talk about:
Colossians 2:12
Buried with him in baptism, wherein also ye are risen with him through the faith of the operation of God, who hath raised him from the dead. 13 And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses;
1 Thessalonians 4:16
For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the
dead in Christ
shall rise first:
This is an example of how you interpret scripture out of context. The dead in Christ rising first is not a reference to the order of resurrections, it's a reference to the order of events as they relate to believers when Jesus comes. After He descends from heaven, what will happen first is the dead in Christ will be resurrected. Then, those who are alive and remain will be caught up together with the resurrected dead in Christ to meet the Lord in the air.
Have you ever wondered why the body of the beast is cast ALIVE into the lake of fire?
Revelation 19:20
And the beast was taken, and with him the false prophet that wrought miracles before him, with which he deceived them that had received the mark of the beast, and them that worshipped his image. These both were cast
alive into a lake of fire burning with brimstone.
I don't see that as having any relevance to this particular discussion. Do you imagine that the beast and false prophet are human beings? They are not. Do you not know that the beast existed before John wrote the book of Revelation? He said the beast "was, is not, and shall ascend out of the bottomless pit" (Revelation 17:8). So, if the beast was a man he is at least around 2,000 years old by now.
No, prophetic beasts are kingdoms.
Daniel 7:23 Thus he said,
The fourth beast shall be the fourth kingdom upon earth, which shall be diverse from all
kingdoms, and shall devour the whole earth, and shall tread it down, and break it in pieces.
But the rest of the DEAD wicked are cast in later.
Revelation 20:5
But
the rest of the dead lived not again until the thousand years were finished.
Why are you referring to the rest of the DEAD in relation to the beast and false prophet after talking about them being alive? The rest of the dead refer to unbelievers who are dead in contrast to the dead believers that John referred to previously in verse 4.