Revelation tells us that the End of Days will begin with the opening of the first seal, which releases the first of the horsemen of the apocalypse. The second, third, and fourth seal similarly release the remaining horsemen. With the opening of the fifth seal, we witness a more complex scene:
And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held:
10And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?
11And white robes were given unto every one of them; and it was said unto them, that they should rest yet for a little season, until their fellowservants also and their brethren, that should be killed as they were, should be fulfilled.
In reading the literature available on the web, the most discussions get bogged in the fine points of the passage. Looking at the passage in broad strokes, we can see that it indicates a coming martyrdom of Believers, where Christians are not only persecuted, but also killed for their beliefs.
Though there has been scant coverage in the mass media, in many parts of Africa and the Middle East, where Death and Hades have brought conflict and death, the slaughter of Christians has become quite widespread. In the case of Syria, hundreds of thousands of Christians have had to flee for their lives as ISIS and other rebel groups have taken to slaughtering them.
Some news links:
http://www.mercatornet.com/demography/view/christian-persecution-increasing-worldwide/17010
http://www.acnuk.org/persecuted
It should be remembered that in the early days of the Christianity, during the time that Paul was spreading the word of God to the non-Jewish world, all the churches were in the eastern Mediterranean region. Even in Revelation, Paul begins by writing:
3Blessed is he that readeth, and they that hear the words of this prophecy, and keep those things which are written therein: for the time is at hand.
4John to the seven churches which are in Asia: Grace be unto you, and peace, from him which is, and which was, and which is to come; and from the seven Spirits which are before his throne;
Perhaps there is some meaning to the fact that the first martyrs of Christ were killed in the same regions where present day martyrs are being killed. Given the scale of the killings, the ongoing threat to Christian lives, the geographical scope of the killings, and the overlap with the martyrdom of the first Christians, I cannot help but believe that the 5th seal has indeed been opened.
The opening of the sixth seal will be very obvious to the whole world.