In The Tripersonal God, Gerald O'Collins examines the roots and development of Trinitarian belief, drawing on three areas for reflection:

Testimony to the tripersonal God in the scriptures - both the Old Testament background and the teachings of Paul and the gospel writers

The development of Trinitarian doctrine from the second-century writers and the early councils of the Church through medieval theology and modern challenges

Major Trinitarian issues of today, such as naming the Trinity, the distinct personal existence of the Holy Spirit and Trinitarian imagery

A comprehensive, contemporary inquiry, The Tripersonal God illuminates the historical and scriptural roots of belief in the Trinity and clarifies contemporary trends in Trinitarian thought.