Ummm... Some of us have FOID cards without actually owning a firearm. There are a number of reasons, the first being that we want to keep the option of owning a firearm on short notice open. It also has to do with reasons as varied as being able to go shooting with friends, purchasing ammo as presents, etc. Not everyone with a FOID card is a FO.
Gun Registration is gun confiscation in slow motion:
http://gunwatch.blogspot.com/2012/12/gun-registration-is-gun-confiscation.html
Ask the Deputy for a warrant. If they don’t have one don’t let them in your home and don’t answer any questions.