This is what many ask...even believers.The souls of those who had been killed because of the word of God were in heaven and they called out in a loud voice, “How long, Sovereign Lord, holy and true, until you judge the inhabitants of the earth and avenge your blood?”
Don't misunderstand, God gets angry with our sin, but He does not sin in His anger. He is not slow, but longsuffering, and He gives us plenty of time and opportunities to repent and turn to Him.
Daniel chapter 2 describes the future and shows us that God has a plan, and will do things in HIs time!
Verse 44 says ‘In the time of those kings, (the clay mixed with iron), the God of heaven will set up a kingdom that will never be destroyed, nor will it be left to another people. It will crush all those kingdoms and bring them to an end, but it will itself endure for ever. This is the meaning of the rock cut out of a mountain, but not by human hands, (verse 34).
We are to ‘stand firm and hold fast to the teachings we have received.’ The teachings we have been passed down from those who were there with Jesus. And we are not to be deceived into thinking that Jesus has already returned, (verses 2-3), because the things that have been set must happen first, and on top of that, Jesus himself said that when he returns it will be like lightening going across the sky and lights it up from one end to the other’ (Luke 17:24). In other words, everyone will see it.Verse 22, Jesus tells the disciples that ‘the time is coming when you will long to see one of the days of the Son of Man, but you will not see it’ which as I understand it means, “It will not be soon.” And we know that 2,000 years have passed since then. But I think that as we have been in the time of the clay mixed with iron feet in Nebucadnezzar’s dream for some time now, it may not be long.
To many, the fact that it has been a long time means that it is not real, but to those who believe, God has given the whole world time to get to know Him and accept Him. And to those who believe even though they have not seen Him, Jesus blesses.(John 20:29). Everything that He has set in motion will come to pass. We don’t know the day or the hour, but it will come. (Matthew 24:36, & 25:13, Mark 13:32). And those who believe will be saved.