The Didache; earliest baptismal confessions
The oldest Christian manuals confess Father, Son, and Spirit and require repentance, baptism, and a holy life. They do not recast those Three as one undivided, unembodied substance.
Creeds can be useful fences. They become a problem when they are made the definition of the word the Bible already defined. Acts 11, 1 John 4, and Romans 10:9 do not say ‘whosoever shall confess the homoousion.’ They say Jesus is Lord, raised from the dead, come in the flesh.

