When a stranger is at my door, I don't open it until I know who they are and what they want.
This is my approach as well.
I don't simply refuse to open the door for a stranger but they will tell me who they are and what they need before I open the door. I'll make a judgment call from there.
Problem is, most of the time in the daylight hours, if I'm home, I'm outside. There is no screening visitors through the door in that instance. However, if I am in the yard or in the man cave or at the BBQ grill, there is a holstered firearm on my side. Some think that is being paranoid on my own property, but we live in the sticks and there's more to worry about than just criminals. There have been more than one dog attacks close to my home, one was only two doors down. So I'm armed in that instance.
There was a situation recently when I refused to open the door. I was awakened by my wife who told me someone was at the door. I glance at the clock and it is 3:00 a.m. Fearing that someone is in trouble or there is an emergency, I run to the door. I call out, asking who it is. It is a female claiming that she is broken down and wants to come inside and use my phone.
Now at the time there had been several home invasions (4 IIRC) within a mile and in the past few months, and the residents were home at the time. So obviously I'm skeptical, thinking this would be a good story to get into someone's home.
I inform her than she may not come in and that I'm not opening the door for a stranger in the middle of the night, but would call someone for her if she had an emergency. Of course she wasn't interested in that and left, making me feel that my suspicions were justified.