Answering Why People Join ISIS

As yet more of our young people are turned back to the UK after trying to get into Syria to help ISIS, the question being asked is 'why are people willing to go help such a horrific killing machine'?  
There have been a few answers but nobody has been willing to give the real answer which is because of religion.
ISIS is doing the things they are doing in the name of their twisted ideological view of religion.
It isn't atheists turning up at Turkish airports with a map of Syria, it is Muslims who have been indoctrinated into the ISIS philosophy by recruiters who take what is already there and ramp it up further.
It isn't just a Muslim problem either, throughout history religionists of all flavours have used the same tactic that they are fighting for their 'God' and this is just the latest.
I am not sure what the solution is or how you can stop young people who are being told since childhood that their God is great from being driven into a fervour by people with bad intentions but that is the reason.
Our only hope is that religion gradually dies out by itself as we evolve and that does seem to be slowly happening but until the World wakes up and realises religion has always just been a man-made construct to control us, there will always be people keen to exploit those who have yet to make that leap.
Less religion is the only answer.