When he opened the fifth seal, I saw under the altar the souls of those who had been slain because of the word of God and the testimony they had maintained. 10 They called out in a loud voice, “How long, Sovereign Lord, holy and true, until you judge the inhabitants of the earth and avenge our blood?” 11 Then each of them was given a white robe, and they were told to wait a little longer, until the full number of their fellow servants, their brothers and sisters,[e] were killed just as they had been. (Revelation 6:9-11)
There are many times in history that true believers in Christ have been martyred for their faith. They have been killed by communists, Hindus, Muslims, Catholics, and Protestants. In the end times they will be martyred all over the world on an unprecedented scale.
Jesus is willing to forgive all sins of people who repent. But there will be a time when even Jesus’ patience as run out. He will judge the world for martyring Christian.
Nevertheless, we as Christians must remember that it is not our job to avenge our own dead. That is something Jesus will do personally after the tribulation. We are to wait patiently for him to come. In the meantime, we must glorify him by remaining peaceable and preaching the gospel of love to everyone, including those who kill us. We must not become like those religions that kill their enemies. Rather, we need to show our love by dying to save our enemies.