In ancient times, people were particularly afraid of homophones, and they were unlucky homophones. The "sill" of the threshold is actually a group of homonyms with the uneven "Kan", so the sill is equivalent to "Kan". It is unlucky for people to step on the threshold, because it implies that you will bring some difficulties.
And each of us hopes that our life will be smooth sailing and we will never encounter any bumps. Just like a bumpy road is difficult to walk, a bumpy life is also bitter. So we can't set foot on the threshold of the temple, but cross the threshold, cross the hardships in life and be happy all our lives.
There is also a saying that the threshold of the temple is actually thinking about the shoulders of the Buddha. We all know that the Buddha is sacred and can bless our peace and joy, so it is extremely disrespectful to go to the Buddha's shoulder. After all, our soles are dirty. Such shoes stepping on the Buddha's body will definitely annoy the Buddha. Everyone who walks into the temple is in awe. We can't step on the threshold and do something disrespectful to the Buddha.
Whether these two statements are correct or not, we still have to abide by an unwritten rule that the threshold of a temple cannot be stepped on. Stepping on the threshold is actually a kind of injury, and we have an obligation to protect every building in the temple.