Their will be two groups of believers in Christ in the third heaven! Raptured Saints are believers who accepted Christ (including all children under the age of accountability) during the Dispensation of Grace! This group will be snatch up to the clouds of Heaven suddenly to meet the Lord in the air!
Tribulation Saints are believers that will accept Christ after the Dispensation of Grace during a time of intense tribulation! Most will be martyred for their faith in Christ!
SCRIPTURES RELATING TO RAPTURED SAINTS
And hath raised us up together, and made us sit together in heavenly places in Christ Jesus. (Ephesians 2:6)
To him that overcomes will I grant to sit with me in my throne, even as I also overcame, and am set down with my Father in his throne. (Revelation 3:21)