This ought to help you understand your mother. I’m glad I listened to mine. https://gotquestions.org/Trinity-Bible.html
That does nothing to help me ‘understand’ my mother’s sitting in church year after year misapprehending the nature of something so integral to Christian belief as the Trinity.
As for myself, I believe that doctrine is a pastiche put together so that Christianity would not be seen as being polytheistic while being polytheistic. But I’m a real heretic. LOL