Don't like ISIS? Then change them from within; it's the statist way.

ISIS claim to be a State, the clue is in the name. 

We claim that ISIS imposing their will on others by force is wrong, so they must be stopped. Joining ISIS and changing them under their own rules is obviously doomed to failure. 

Our state imposes its will on us by force, why isn't that wrong? If you don't believe this is true, try breaking a state law and seeing if force results, either the confiscation of your property or your freedom. 

Why is it that you think that you will have more success in changing things in a so-called democracy? 

(a) You only get to vote every few years. 
(b) The manifestos are decided internally by the parties, not by the public. 
(c) You can only vote for a basket of policies, not a single issue, e.g. what if you agree with benefits for the poor, but not with nuclear weapons? 
(d) The differences between the manifestos are trivial, seldom amounting to more than a minor change in an existing policy. 
(e) Manifesto promises are seldom kept. 
(f) Parties claiming that the opposing parties policies are wrong and harmful, seldom repeal them if elected later, so how wrong and harmful were they?  

The state citizen has no real power. Money talks; it is the rich special interest groups that influence individual politicians to enact policies that favour them, at your expense. 

The left/right paradigm merely provides political theatre by letting you have the fig-leaf of choice between tweedledum and tweedledee presented by the ruling elite.