The controversy over the relationship between the Father and the Son (and, later, the Spirit) broke out in the first half of the fourth century AD, but the source of the controversy goes back 1,700 years before that, to Moses. 

Why do we need creeds? That might be a question you have asked or that a family member or friend has asked you after finding out you speak a creed in the Divine Service. However, in reality, there is no Christian without a creed.