When the Lamb broke the fifth seal John immediately got a vision of the heavenly temple; and his focus was under the altar of incense where he saw the souls of those who had been slain.

Who are the souls under the altar? These are the souls of the redeemed who were martyred very early in the Tribulation. It is possible that they were saved just after the Rapture of the church, as a result of the preaching of the 144,000 witnesses.

There is another group in Revelation 7:9-17, that is mentioned as a “great multitude” and as “ones who come out of the great Tribulation.” This is possibly a later group, which are from the last half of the Tribulation, and that is mentioned in Revelation 6:11 as “their fellow servants and their brethren who were to be killed even as they had been…” Or, it may be that…