These articles explore the Trinity as believed by mainstream Christianity.
The Philosophical Roots of the Trinity: Alexander and Arius
Logical problems of the Hypostatic Union
John 10:31-36: Jesus passes up opportunity to teach Trinity
Psalm 90:2: God is “Everlasting to Everlasting”
Baptizing in the “name” of the Trinity: A Trinitarian prooftext
Trinity/Godhead Passages: A List