The trinity was invented to avoid accusations of polytheism, but as usual with religious apologetics it just adds more confusion.

Jesus, god, and the holy spirit must all be one, otherwise the religion is not monotheistic.

But if they are all one, why ever distinguish between them?

So believers arbitrarily assign different roles to their three different gods while pretending it’s all the same guy. God is immune to logic, and many christians dare not question their own salvation. It is moral and intellectual cowardice, and it is killing us all.