"Therefore, heaven will demote to a great post, so people are also" means "great post" and "being a person" means.

The original text "Therefore, Heaven will assign a great responsibility to the people of Sri Lanka"

Great responsibility: "Great" takes its original meaning, size, and. "Ren" refers to the task, mission,

Si people: "Si"-before and after the coherence, it is the auxiliary word "Si people"-person, person,

whole sentence: So when God wants to deliver an arduous mission to someone, (it must be something)