Yes, citizens could be the key to fighting ISIS because ISIS fighters may not expect citizens to rise up and revolt against them. It could be used as a surprise tactic. Plus, the citizens are there, among the ISIS fighters now. They should help get rid of the ISIS fighters in their towns.
The Iraqi citizens are the people who suffer most due to ISIS. They must do everything within their power to eliminate this global threat. Members of ISIS do not care who they kill. They will kill Iraqi citizens just as quickly as people from other countries. Citizens must join the fight.
Yes, citizens could be key in the fight against ISIS. ISIS preys on people's fears to gain strength, like any other bully. Citizens have more power than they think, and if they assert that power, they could very well be the key to eliminating or at least diminishing this terrorist group.
Governments across the world should not put the onus on civilians to fight well-organised and well-equipped terrorist organisations like Islamic State. They should only be faced, in ideal circumstances, by trained soldiers who can fight them on an equal footing. Encouraging civilians to take them on is effectively to encourage them to commit mass suicide.