human rights and wrongs

In the late 1930's British people went to fight in the Spanish Civil War, a different sort of war I know but people on both sides lived and died the same. They were not trying to create a new country just change the way a country was run.The British people who left to fight if they were lucky returned, what happened to them?

There is a school of thought at the moment which says if you go to fight for the Islamic State then you should lose any British citizenship you have. As we all know there is also a school of thought which says no you cannot do this because it might breach there human rights.

So who is right?

We have people who have left this country to join various groups in Syria and Iraq where they are fighting to create an Islamic State and no one who does not conform to the organisations ideas appears to be safe, we have seen these actions before.

If you have left this country to help with the creation of this state and support its aims, its objectives and its means of operation have you given up citizenship of this country for citizenship of that state?  Especially when from what we are told and what we see this organisation has no respect for the human rights of others.

We are told that some of the people who have fought in Syria and Iraq have already returned, some broken and disillusioned, others biding there time for what? Are those who say take away there citizenship right?  Should we not because it breaches there human rights? How do you know if someone has gone to fight and come back?

So who is right?