Revelation 6:9-11 ESV When he opened the fifth seal, I saw under the altar the souls of those who had been slain for the word of God and for the witness they had borne. [10] They cried out with a loud voice, "O Sovereign Lord, holy and true, how long before you will judge and avenge our blood on those who dwell on the earth?" [11] Then they were each given a white robe and told to rest a little longer, until the number of their fellow servants and their brothers should be complete, who were to be killed as they themselves had been.
The question of burial or cremation is within the realm of Christian freedom. A person or a family considering this issue should pray for wisdom (James 1:5) and follow the conviction that results.
Hebrews 6:4-6 NIV It is impossible for those who have once been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit, [5] who have tasted the goodness of the word of God and the powers of the coming age [6] and who have fallen away, to be brought back to repentance. To their loss they are crucifying the Son of God all over again and subjecting him to public disgrace.