18 And then those that fell asleep in Christ were lost.
1 Corinthians 15:18 Cross References - LITV
1 Corinthians 15:6
6 Then He appeared to over five hundred brothers at once, of whom the most remain until now, but some also fell asleep.
1 Thessalonians 4:13-14
1 Thessalonians 4:16
16 Because the Lord Himself shall come down from Heaven with a commanding shout of an archangel's voice, and with God's trumpet. And the dead in Christ will rise again first.
Revelation 14:13
13 And I heard a voice out of Heaven saying to me, Write: Blessed are the dead, the ones dying in the Lord from now. Yes, says the Spirit, they shall rest from their labors, and their works follow with them.