To believe in

elieve in是“信任,信仰”的意思.
To believe in 是believe in 的不定式,to在这里只是介词作用,在这里没有实际意义.
给你举几个例子好了.
To believe in Marx is to believe the truth.
信仰马克思就是信仰真理.
It's difficult to believe in you again.
很难再相信你了.
若还有疑问,