OP didn't say she didn't open the door because she was anxious - that came later. She said she didn't do it because she thought it was a religious person or a cold caller and she ignored the banging on the door. Fair enough.
It turned out to be her neighbour who was panicking because her child had hurt himself. Who among us hasn't panicked and asked for help? I have, but perhaps other people on this thread have been lucky so far. Anyway, for anyone who doesn't know, sometimes people help us and sometimes they can't be arsed.
The neighbours are now upset with OP because she not only ignored them but told them that. Not that she was anxious but that she heard the knocking and just ignored it. Not a wise thing to do but she can't take it back now.
I can see why the neighbours were a bit annoyed about even if people are insisting they can't. I wouldn't have shouted at her. There's no point. The boy is all right. Instead I would have said quietly to my husband: "Okay. So in future I'm not going to piss in her ear even if her brain is on fire" and my husband would have said: "And neither will I." And that would be it.
OP made a mistake. We all do it. We have to live with our mistakes and the result of hers is that her neighbours don't like her any more. Oh well, there must be other neighbours.
Personally I think it is weird, antisocial, selfish, unthinking whatever not to open the door, answer the phone, talk to people in the street and above all to help people. I like doing that. I'm not a fool and I don't put myself in danger. I'm not perfect either and there are times when I've thought: "Oh shit! Would it have killed me to just stop and help?"
People have helped me - once in a genuine emergency and other times when I was in a pickle or when I was just panicking like we all do from time to time. I've paid it forward with other people. That's all we can do. It's nice feeling. Certainly nicer than posting on Mumsnet about how your neighbours hate you.
If you don't agree with helping people that's fine. But don't tell me that it's me that has the superior attitude.