[kosciusko51]

That’s not the classic definition where I am from, since the Trinity is essential to being a Christian, let alone being an evangelical.

[Cronos]

Well then how would you define an evangelical? Since "Evangelical" groups reject creeds like the Nicene creed, there is no "classical definition" --

you do realise that the Unitarians also were defined as Christian as late as the 50s (Eisenhower was Unitarian)

[Cronos]

The dictionary definition of evangelical is belonging to or designating the Christian churches that emphasize the teachings and authority of the Scriptures, especially of the New Testament, in opposition to the institutional authority of the church itself, and that stress as paramount the tenet that salvation is achieved by personal conversion to faith in the atonement of Christ.

By this definition, you can't reject the Oneness Pentecostals right to be called evangelicals

[Cronos]

What do pentecostals believe

Some such “classical Pentecostals,” however, do not believe in the Trinity; they are known as “Oneness Pentecostals” or “Jesus Only” Pentecostals. Their largest organization in the U.S. is the United Pentecostal Church, but most of their congregations use the word “Apostolic.”

or you can Read what the United Pentecostal Church says of itself.

Since there is no central doctrinal statement besides "Bible literally" and "by grace alone" - then the Oneness ARE Evangelicals.