Why does the doctrine of the Trinity matter?

A reflection on Paul's Trinitarian blessing in 2 Corinthians 13:14.

I. What is the Trinity?

II. What the Trinity is not:

1. Tri-theism.
2. Modalism.
3. Adoptionism.

III. Why it matters:

1. It is Biblical.
2. It reveals God's nature.
3. It is a test of orthodoxy.
4. It tells us who we are.

IV. Conclusion