What does it mean to enter the mountain gate carefully, although it seems that the building is easy to collapse?

Carefully walked into the door, it seems that although it is a building, it means:

In the book, I specially named the meaning of Shanda Temple. In the sixth book "Lu Shao Hu Temple", it is mentioned that Lu met an ancient temple on a mountain road. When you enter the mountain gate, look carefully. Although it is a gate, it will collapse. This temple is a crock temple, where you meet and occupy this temple. Lu could not compete with the two of them, and finally invited Shi Jin to kill them, which did great harm to the temple.