The New Catholic Encyclopedia, Volume XIV, p. 295:
". . . It is difficult in the second half of the 20th century to offer a clear, objective and straightforward account of the revelation, doctrinal evolution, and theological elaboration of the Mystery of the trinity. Trinitarian discussion, Roman Catholic as well as other, present a somewhat unsteady silhouette. Two things have happened. There is the recognition on the part of exegetes and Biblical theologians, including a constantly growing number of Roman Catholics, that one should not speak of Trinitarianism in the New Testament without serious qualification. There is also the closely parallel recognition on the part of historians of dogma and systematic theologians that when on does speak of an unqualified Thrinitarianism, one has moved from the period of Christian origins to say, the last quadrant of the 4th century. It was only then that what might be called the definitive Trinitarian dogma 'One God in three Persons' became thoroughly assimilated into Christian life and thought . . . it was the product of 3 centuries of doctrinal development."