You might be enraged at the idea of doing homework on a Saturday if you consider your weekends sacrosanct — meaning they are too special or important to interrupt.
Sacrosanct is often used to describe religious rituals and traditions, which isn’t surprising considering that this adjective comes from the Latin word for something that is protected by a religious sanction. A church, for example, might consider its Sunday service to be sacrosanct — a very important and holy ritual that cannot be changed or canceled. It’s a bad idea to criticize or change any custom or tradition that people consider sacrosanct — they won’t be happy about it.