what is this English grammar in the following statement?

"For in a broad sense, spirituality is part of our human nature and common to all people."

I mean, what is the purpose of the word "for"?

why don't we just omit "for" and just write "in a broad sense" as a preposition?

“Nhất,tam, ngũ bất luận – Nhị, tứ, lục phân minh” nói về thể thơ nào? 

A. Thơ lục bát

B. Thơ song thất lục bát

C. Thơ Đường luật

D. Thơ tự do