There's someone who wants into the building where I live and I'm not going to let them in.
Is there a specific reason why you won't let them in?
Well, I can't because I've never seen them before.
If it's not someone you recognize then for the safety of you and other residents then I think you are making the right decision. If they live there they should have an access code, card, or key to get in.
Plus, there is a chance they could be bad people and they could be dangerous. So, I'm not going to let people I don't know into the building.
There is definitely that chance and you wouldn't want to be responsible for allowing them access. If they truly belong inside the building then they'll call someone to help them out.