God's name for the rapture

A lot of bible believing Christians, including me, use the word "rapture" to describe the event mentioned in 1 Thessalonians 4:13-18.  The word "rapture" is not found in the English bible, but the idea is.  Here's what God calls the rapture.

"The first resurrection"

Here is a passage from Revelation 20 about "the first resurrection":

4 And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years.
5 But the rest of the dead lived not again until the thousand years were finished. This is the first resurrection.
6 Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.

This is actually another proof of a post-trib rapture because those that were beheaded for not worshiping the anti-christ are part of the first resurrection.  How could they be part of the first resurrection if the rapture already happened before the tribulation?

Another name for the day of the rapture is "The Day of the Lord".  The bible mentions the day of the Lord many times throughout the bible.  I will say however that there appear to be multiple days of the Lord.  Every time it's mentioned though, it's talking about a day where God judges a group of people.

Isaiah 13:6 says:

Howl ye; for the day of the Lord is at hand; it shall come as a destruction from the Almighty.

This was a prophecy of the coming fall of Babylon which happened around 536 BC.  This prophecy took place about 100 years before that.

When Paul describes the rapture in 1 Thessalonians 4, he goes on to call it "the day of the Lord" in 1 Thessalonians 5:

2 For yourselves know perfectly that the day of the Lord so cometh as a thief in the night.

There will also be one last day of the Lord which will happen when heaven and earth pass away.  2 Peter 3:10 says:

But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up.

The reason that the day of the rapture is called "the day of the Lord" is because God begins to pour out his wrath on that day.

The rapture happens when the 6th seal is opened. When the men of the earth see Jesus coming in the clouds, here's what they say:

Revelation 6:16-17:

16 And said to the mountains and rocks, Fall on us, and hide us from the face of him that sitteth on the throne, and from the wrath of the Lamb:
17 For the great day of his wrath is come; and who shall be able to stand?

Jesus talked about how the rapture would happen on the same day as his wrath.  See this passage from Luke 17:

26 And as it was in the days of Noe, so shall it be also in the days of the Son of man.
27 They did eat, they drank, they married wives, they were given in marriage, until the day that Noah entered into the ark, and the flood came, and destroyed them all.
28 Likewise also as it was in the days of Lot; they did eat, they drank, they bought, they sold, they planted, they builded;
29 But the same day that Lot went out of Sodom it rained fire and brimstone from heaven, and destroyed them all.
30 Even thus shall it be in the day when the Son of man is revealed.

The only reason I use the word "rapture" rather than "the first resurrection" is because rapture is more commonly used among modern day Christians.