With the postal survey on marriage equality coming up, there's been a lot of discussion about this issue recently. How do you feel about marriage equality?
(Note: They may not understand that phrase – if so, maybe explain that some people describe this as ‘same-sex marriage’.)
Start with an open question — you are never going to find out what someone thinks unless you let them tell you first! And remember, this may be the first time they have really thought about this issue, so give them the time and space to work this through for themselves before you start digging deeper into the discussion.