We could imagine that the peoples simply did not like to hear about Jesus Christ, his victory on the cross, his resurrection from the dead, and his ascension into heaven. The context, however, makes clear that there is more to it. For these witnesses did more than speak of Jesus Christ; they also had power (remember the altar and their prayers) to rain God’s plagues upon the earth in step with the details of Revelation 8:1 – 9:21. The ungodly recognize that link. Specifically they hear the saints ask that God hallow his name, advance his kingdom, etc. There is something about the church of Jesus Christ that threatens their way of life, their prosperity and peace of mind. (It is striking that word “torment” in v. 10 is the same word as appeared in Revelation 9:5.) To the minds of earth-dwellers the death of these witnesses guarantees the end of their prayers and so also the end of the plagues and torments they can somehow bring upon the earth.
10 and those who dwell on the earth will rejoice over them and make merry and exchange presents, because these two prophets had been a torment to those who dwell on the earth.