That's what I meant. You can't descriminate and refuse sale based on religion, race, sex, etc.
You certainly can.
But if you advertise your willingness to sell your property to the general public, the rules change.
You can't say you are willing to entertain bids from the general public and then discriminate against bids from the general public.
If tomorrow I decide that I want to sell my home, but only to a person who attends my local parish I can certainly do so.
But it has to be a one-on-one transaction.