God as Trinity: Why It Is Not One God in Three Modes

There are two classic wrong turns here, and they fail in opposite directions. This is the first.
One old explanation held that God is only one person, not three, but that he revealed himself in various modes or roles - appearing as Father, then as Son, then as Spirit. A related idea said Jesus was not God in his essence at all, but that God was simply working through him.
Of the wrong turns, the modes explanation is the more thoughtful one. It takes God's oneness seriously, which is more than can be said for some alternatives. But it does not hold up to the text.
Here is why. The Father, Jesus and the Spirit appear in the same passages, together. Go to the Jordan at Jesus' baptism: the Son is in the water, the Spirit descends, and the Father speaks from heaven. Three at once, in one scene. If God simply switches modes, that moment is incoherent. Elsewhere Scripture groups the three together and speaks of them interchangeably - one formula, one name - in ways a single actor changing costume cannot explain.
Their roles do not occur one at a time. They overlap.
Scripture links:
- Matthew 3:13-17 - Son baptised, Spirit descending, Father speaking.
- John 14:16-17 - I will ask the Father, and he will give you another Helper.
- Matthew 28:19 - one name, three persons.
One actor cannot play three parts in the same scene.