Some Key Terms:
Arianism

"There was a time when the Son was not" - Arius taught that Jesus is God's greatest creation, not true God.

 

Council of Nicaea (325 AD) & Constantinople (381 AD)

Church councils that formally declared Jesus to be true God

 

Theotokos (Osoókos)

Greek: "God-bearer" - the title given to Mary, affirming that Jesus is fully God

 

Nestorianism

The teaching that Jesus the man and the eternal Word of God are two distinct persons - condemned at Ephesus (431 AD) and Chalcedon (451 AD)

 

Mystery

In Scripture, something God intends to reveal-but which cannot be fully grasped by human intellect alone