Not sure where to start?
Try our reading paths — books in order, with a guide for each step（5）→
The most widely confessed statement of Christian faith. Grown from the second-century baptismal creed of Rome and fixed in its present form by about the eighth century, its twelve articles follow the Trinity: Father, Son and Holy Spirit.
The creed of the first ecumenical councils. Against Arius, Nicaea (325) confessed the Son "begotten, not made, of one substance with the Father"; Constantinople (381) expanded the article on the Holy Spirit. Shared by East and West.