People who believe your lies might make bad decisions because of them.請問because of them 在這裡的文法用法及意思，?

An attempt to answer only:-
People who believe(and because of)------S +vt
your lies-----------direct object
might make bad decisions--------adverbial clause.
-----------them=your lies; not the word"decisions"

先說說意思:
because of them中的them是指your lies

文法上是複合句子中的解釋部份，例如小學學英
I like him because XXXX(形容詞作描述)
但是大學寫英文便會
I was unable to finish the work because of my lack of the skills required.(解釋的內容是"because of"一些客觀或片語式的原因，這裏的名詞/分詞片語是lack of skill required)

你問的這句假如變回小學的句子便是：
People who believe your lies might make bad decisions.本身已經是完整陳述意義表示主角(People)因(believe your lies)果(might make bad decisions).
但是假如想強調人們這錯誤決定"就是因為甚麼"的話便要把主體(人們)和受體(make bad decisions)反轉過來再寫句：
It is because of believed your lies that people might make bad decisions.

當中作者強調的意義包括
People believe your lies
Because of your lies (or because you 先lied)
People might make bad decisions
所以作者想特別在陳述基本因果邏輯後強調主因

所以是一種complex附加強調某一重點的寫法。