Paul is addressing the concern of believers. I call your attention to Verses 13 and 18 below. There is no need for Paul to address the resurrection of the unbeliever!
1 Thessalonians 4:13-18
13. But I would not have you to be ignorant, brethren, concerning them which are asleep, that ye sorrow not, even as others which have no hope.
14. For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him.
15. For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not prevent them which are asleep.
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:
17. Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.
18. Wherefore comfort one another with these words.
What is different, OR, is that when resurrection was taught in the past, prior to what we believe to be previously unrevealed truth, or mystery, is that both groups are mentioned. We see that here:
Daniel 12:1-2
King James Version (KJV)
12 And at that time shall Michael stand up, the great prince which standeth for the children of thy people: and there shall be a time of trouble, such as never was since there was a nation even to that same time: and at that time thy people shall be delivered, every one that shall be found written in the book.
2 And many of them that sleep in the dust of the earth shall awake, some to everlasting life, and some to shame and everlasting contempt.
So if the argument offered here is valid, why does Paul not mention the destruction of the wicked also?
Well, one primary reason is that through New Testament revelation we see teaching concerning resurrection not previously revealed. Namely...not all shall sleep, or, die.
1 Corinthians 15:50-51
King James Version (KJV)
50 Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption.
Paul first makes the point that in our physical bodies, we cannot enter the spiritual abode of God. This is something to keep in mind when looking at passages concerning the Kingdom of God, meaning, this speaks of a Kingdom beyond the Kingdom we generally acknowledge as the reign and rule of God in the hearts of men.
This prefaces the next statement:
51 Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed,
Again I would agree with you that in view the audience are believers, however, it is better to say that the event itself involves born-again believers, rather than one trying to say, as they do with Hebrews, that the audience are all saved (and this point, OR, is just an aside, it has nothing to do with our discussion, past or present).
The MYSTERY here is that...not all believers are going to die. There will be a time when glorification will take place for those that are still physically allive.
In Revelation 20...all are dead. Some are raised, some are not. We do not see a general resurrection mentioned in either case. And while I will agree it is completely reasonable to see this as simply not mentioning the resurrection of the wicked, I have to reject this based upon the fact that we have a resurrection in Revelation 11, another in Revelation 20 concerinng believers (Tribulation Martyrs), and a thousand year time-frame (and a period of time despite how long one makes "a thousand years to be") between one resurrection (of the just) and the other (of the dead).
Which leads one to a more reasonable view that there are multiple resurrections, the resurrection of the Just being of the same type and qualitatively different from that of the dead.
Continued...