When a person knocks on my door on shabbos, coming to visit without any plans for a visit, I prefer not to answer the door. I am very uncomfortable with unplanned visits, they are very stressful for me. I do not want to sit and chat. I feel that it would not be possible to answer the door and say that I am not able to sit and talk at that time so I don’t answer. This has happened several times. In an almost all cases the person who came to the door did not know whether I was home or not.
What is the correct thing to do in these situations?
Should I apologize to the people who have come and for whom I did not answer the door?
You are not halachically obligated to answer the door when someone knocks, the same way you are not obligated to answer the phone when someone calls you. There are times when a person wants or needs their privacy or quiet time, without being disturbed. (Unlike texting, where everyone in the world has the right to disturb whoever they want, whenever they want, and if the person doesn’t respond to them, they get all insulted.) Practically though, if the person does know that you are home, it is an insult to them, and you should excuse yourself in some way. If the person doesn’t know that you are home, it is better not to say anything to them, because then you are telling them that you knew, but weren’t interested in talking to them, which would be insulting.