I don't know that we need them or want them, but I am sure the best thing to do is ignore them.
I am a natural atheist. My parents took me to church, but I never thought any of it was real.
I think religion can bring comfort to people, but I don't think it is necessary for a happy life.
Just ignore them. I used to argue with people like that, but really there is no point. Some of them honestly think they are doing good things. I can't fault anyone who really believes they are being helpful - I can get really annoyed, but I can't blame them.
As long as they don't want to burn or stone me, I can live with them :-)