Maybe the people on here who live in countries with ID cards could spell out exactly what information they give. My understanding is that it's fairly basic. However, if the police (or anybody else) has any reason for suspicion they have access to other databases.
To be honest, a system which simplifies life by collating verified information such as name, DOB, address, NI and NHS numbers etc seems absolutely fine. I already have it all in a little plastic folder, if anybody's interested (which most most people aren't).
If we get to the situation where government is instructing us to carry around personal information such as religion, ethnicity, sexual orientation, political affiliation, etc, I think we should start to be worried not only by the requirement, but what kind of government we have. An ID card with that kind of information would be the symptom of a repressive government and we should vote them out, before things go to far.
However, I really don't think we're at that stage BUT, make no mistake, government already holds all sorts of information about all of us. I can't see that ID cards would make any difference.