Resurrections

I accept that the Thessalonians passage describes only one resurrection – that of the dead in Christ.

But Revelation mentioned two groups of the dead who lived again: the first group lived at the start of the thousand years; the second group lived not again until the thousand years were ended.

The first was called the first resurrection. To say there was a first, implied that there was to follow another – a second. It also implied that both resurrections would for all intents and purposes have the same nature. 

How do you fit one passage with the other?