For myself, I think you need to do several things, but the interesting one for me is the philosophical battle. You have to address the ideas and show what is wrong with them.
To do that, you must understand what has gone wrong in Islam and then figure what might fix it.
The things you can't do: assume such people will be horrified the same way as we are; or close your eyes and wish the problem will disappear.
We have to neutralise the power of the ideas. Then the number of twits who respond to them will be limited.
I suspect ridicule may be one of our most powerful weapons. Also a willingness to put up with it and keep on living because as tkc points out, there are other problems.
Lived through the IRA during a period when US citizens financed terrorism in the UK. These things end.