Those 4 Billion people aren't running an army. Those 4 billion are the ones who willingly run headlong into the spear while the ones telling them about Armageddon sit back and reap the rewards. It's the same rhetoric as everything else: "They're going to murder and enslave all the white babies", "The government is going to take our guns and enslave us", "The Germans are a persecuted people and we must reclaim our honor or be destroyed", etc, etc, etc.

1. Never believe a politician. Those candidates are saying anything that will attract money, voters, and eyeballs.
2. Never believe anyone trying to scare you
3. Never believe governments(or states in this case)
4. Armagedon cult just so happens to be the best excuse for everyone involved. "Those crazy IS thugs think the world's going to end, see it's not our fault they're all just insane over there! Even if we hadn't invaded and caused the deaths of hundreds of thousands of people the same thing would have happened" or "If you're a Muslim and you don't come to the caliphate and prepare for the end of days you must be collaborating with the Jews and Christians, therefore we declare you a takfiri" or "Come die for us, it's for the noble cause of bringing peach to the world". They'll use any reason they can to get what they want or be able to provide "justification" for killing those who get in the way.
5. IS is a military organization, you don't get to deal in vaguities when you're commanding tens of thousands of men fighting against the pretty much the whole world at this point, unless you're lying to someone.
6. By the virtue of being written down 1400 years ago, armageddon is going to happen. If it's predetermined to happen, why do you have to provoke the invasion required for the end times battle? If the Gog and Magog are so wild and lawless, why do you have to be the one to start the battle?

I'm not a Muslim, and I don't know a whole lot about Islam so I could be off base on the last one concerning Muslim involvement in the lead up to the End of Days, but nothing I saw indicated it was required.