Manichaeism almost becoming state religion of Roman Empire

Question

I am reading Yuval Noah Harari's Sapiens: A Brief History of Humankind, an excellent source throughout.

At one point (on p. 270 in the German edition) the author mentions a turning point in history where Manichaeism, a dualistic religion whose founder lived in the 3rd century AD, could almost have become the Roman Empire's state religion.

What specific time or event may he be referring to?

Answer 1

Manichaeism rapidly spread west into the Roman Empire. From Egypt it moved across northern Africa (where the young Augustine temporarily became a convert) and reached Rome in the early 4th century. The 4th century marked the height of Manichaean expansion in the West, Manichaeism