If you say you dont support terrorism, but you advocate to tear down any defense a nationstate has against its enemies, especially boarder control, police force and the law that governs their ability to make use of the tools, you are at the very least partially responsible when these incidents happen.
But if you say you dont support terrorism and you fight tooth and nail against any moves, legislative or otherwise to observe, analyse and control the environments that breeds these domestic terrorists like paris suburbs or zones like molenbeek, if you shout down anything and anyone that makes an attempt to analyse causation and corelation, you are in cohorts.
And if you finally say you are against terrorism, but fight against state control of mosques, the attempt to install oversight and work actively to import pretty much exclusively people not from just poor countries (there are plenty of poor asians or eastern europeans), but people from regions that exhibit frightening levels of islamic religious extremism, express positive views about the work of people who sabotage boarder fortifications and help people from these regions to bypass and circumvent the control of law enforcement, i think that, whatever other motives you have, whatever other agenda you follow, you actively and knowingly support terrorism.
I think for all the paragraphs you should be moraly responsible, but for the last paragraph i think you should be held legally responsbile as well.