Like Nonnie, I do not see, Dee, how abusive partners would be able to track down spouses via the ID card, nor why this would be a problem in witness protection. Surely in the latter case, people would be given a new identity and thus new IDs.
As has been said, ID cards have existed for at least a couple of generations in other countries with no indication that runaway spouses, protected witnesses, etc. have been traced by those they wish to hide from. Do they not still keep driving licenses, NHS numbers and cards, etc. If they are not traceable via these, then why should ID cards make them more so??
In answer to those who have mentioned it, religion is not on the ID card, unless your title is Rev.
Please also remember that persecuted minorities like the Jews in Nazi-occupied Germany had to do with prejudice, hate and the systematic policy to annihilate a people, not ID cards. Jews were made to register
with the police, made to wear a gold star to be identified and herded into ghettos.
I find it upsetting that a link can be made by anyone between these events and current proposals re ID cards and speak, not as someone who in lives in a bubble, but as someone who lost ancestors in that horrible time because of who they were. If anyone can prove that ID cards would lead to such persecution again, then I would be the first to object.