What is an "Evangelical"?

Phil Johnson has an conference message on his website in which he explains the history of evangelicalism.

Contrary to the current working definition of evangelicalism, which seems to hinge on diversity (i.e, the definition of the evangelical movement is that it is so ethnically, socially and theologically diverse that it can't be precisely defined), Phil traces the history of the term "evangelical", and the thinking that lay behind it.

Basically there are two key points on which all traditional evangelicals agree on:

1. The authority, inerrancy and primacy of Holy Scripture - that is, the Bible, not popes, bishops or councils, is the authority on church doctrine and practice.
2. The centrality of the Gospel - the notion that salvation is obtained by faith alone, through grace alone. 

Any strand of modern Evangelicalism (or what is currently masquerading as Evangelicalism) which departs from either of these two principles has departed from the bounds of traditional Evangelical conviction.

Phil Johnson has also written in his blog about the death of what has, for the last 50 years, been called evangelicalism. He asserts that its death is neither preventable nor lamentable, and calls all true Evangelicals back to the fundamental issues of sola Scriptura and sola fide.

So, what is an "Evangelical"? Someone who affirms both the authority of Scripture and salvation by faith.