Are buddhists also called brothers and sisters? Usually when speaking about someone who is following the buddha teach is called a monk. But are monks or other buddhists sometimes also called brothers and sisters? Is it common or very rare? And what is the reason behind it?
No, when speaking about a monk, you should use respectful words like 'Venerable', 'Bhante', 'Reverend' etc. If you are speaking of a layman, it's ok to call 'brother' or 'sister' or any other decent way of addressing.