There is a spectrum of Evangelicalism, and not all Evangelicals will answer this question in the same way. There has been an acknowledged difference between Conservative Evangelicals and Open Evangelicals in recent years, and some would argue that they are both different from the kind of Evangelicalism that was found in Anglican churches until the 1950s.
Below are some definitions that have been attempted over the years. If you know of others, or want to add your own, use the box below.
Michael Lawson, an English Evangelical who spoke at the 2009 meeting at VTS, referred to David Bebbington’s definition, now widely used: evangelicalism is a form of Christianity that is CONVERSIONIST, ie believes that lives need to be changed; ACTIVIST, ie expresses the gospel in effort and service; BIBLICIST, ie has a particular regard for the Bible; and CRUCICENTRIST, ie lays stress on the sacrifice of Christ on the cross. Michael felt that the PRIORITY OF PREACHING should be added, and that some attempt should be made to explain that Evangelicals have a PARTICULAR WAY OF READING SCRIPTURE, in the light of what he called the meta-narrative, ie the doctrine of the divinity of Christ (if I have understood him correctly).
Jim Basinger, former President of EFAC-USA, suggested these four distinctives in an Episcopal Evangelical Journal article (vol II No 5): DOCTRINE OVER EXPERIENCE (what the Bible says is true trumps what ‘feels right’ or ‘what I think’); CENTRALITY OF PREACHING; and Holy Communion as a SACRAMENT ADMINISTERED TO MAN, NOT A SACRIFICE OFFERED TO GOD; and an evangelical view of the church as a body defined by its BELIEF AND LIFE, NOT ITS POLITY.
John Richardson, another Church of England Evangelical, makes an interesting point, after referring to the definitions put forward by Martyn Lloyd-Jones and John Stott: ‘The sheer fact that the question has been asked so often, and that answers by such erudite contributors have apparently failed to settle the issue, forces us to acknowledge that evangelicalism is not a set of commonly-held, narrowly-defined, doctrines’ (http://ugleyvicar.blogspot.com/2009/08/what-is-evangelical.html).
Bruce Robison, an Evangelical priest in Pittsburgh, offers this by Kenneth S. Kantzer and Carl F. H. Henry, in Evangelical Affirmations (Grand Rapids, Mich.: Zondervan, 1990), pp 37-38: “Evangelicals believe, first of all, the gospel as it is set forth in the Bible. The word evangelical is derived from the biblical term euangelion meaning “good news.” It is the Good News that God became man in Jesus Christ to live and die and rise again from the dead in order to save us from our sin and all its consequences. The Savior’s benefits and his salvation are bestowed upon us freely and graciously and are received through personal faith in Christ. They are not conditioned on our merit or personal goodness but are based wholly on the mercy of God.
“Evangelicals are also to be identified by what is sometimes called the material or content principle of evangelicalism. They hold to all of the most basic doctrines of the Bible: for example, the triuneness of God the Father, God the Son, and God the Holy Spirit; the pre-existence, incarnation, full deity and humanity of Christ united in one person; his sinless life, his authoritative teaching; his substitutionary atonement; his bodily resurrection from the dead, his second coming to judge the living and the dead; the necessity of holy living; the imperative of witnessing to others about the gospel; the necessity of a life of service to God and human kind; and the hope in a life to come. These doctrines emerge from the Bible and are summarized in the Apostles’ Creed and the historic confessions of evangelical churches.
“Evangelicals have a third distinguishing mark. In accordance with the teaching of their Lord they believe the Bible to be the final and authoritative source of all doctrine. This is often called the formative or forming principle of evangelicalism. Evangelicals hold the Bible to be God’s Word and, therefore, completely true and trustworthy (and this is what we mean by the words infallible and inerrant). It is the authority by which they seek to guide their thoughts and their lives.
“These then are the three distinguishing marks of all evangelicals. Without constant fidelity to all three marks, evangelicals will be unable to meet the demands of the future and interact effectively with the internal and external challenges noted in these affirmations.
“Evangelical churches also hold various distinctive doctrines that are important to them; but nonetheless, they share this common evangelical faith.”
The ‘classical’ definition for Anglican Evangelicals is that of J. C. Ryle, Bishop of Liverpool from 1880–1900. Ryle’s definition, in an essay in his book Knots Untied, uses five headings: the absolute supremacy of Holy Scripture, the completeness of human sinfulness and corruption, the saving work and office of Christ, the inward work of the Holy Spirit in the heart, and the outward and visible work of the Holy Spirit in one’s life. For a full statement of his definition, type ‘Ryle’ into the search box near the top of the column on the right and you’ll see a whole series of posts quoting his essay.
It seems to me that the one thing common to every definition is a higher view of Scripture than is held by other Christian traditions, and I would use that as the single defining characteristic, since all the others flow from it (or are thought to), and the only differences between Evangelicals arise from a different understanding of what Scripture actually teaches. So I would define Evangelicalism as the belief that for Christians the Bible is THE FINAL AUTHORITY FOR ALL MATTERS OF CHRISTIAN FAITH, CHRISTIAN LIFE AND CHRISTIAN WORSHIP. But Anglo-Catholics, and even some liberals, might say the same; Michael is right that we need to point out that we read Scripture in a distinctive way.
Evangelicals have not historically given equal weight to Scripture, tradition and reason, for instance, but have shared Hooker’s view of their respective value: “Scripture with Christian men being received as the Word of God, that for which we have probable, yea, that which we have necessary reason for, yea, that which we see with our eyes, is not thought so sure as that which the Scripture of God teacheth…” (Laws II:7:5) and “what Scripture doth plainly deliver, to that the first place both of credit and obedience is due; the next whereunto is whatsoever any man can necessarily conclude by force of reason; after these the voice of the Church succeedeth” (Laws V:8:2, my emphasis).
Evangelicals also believe that ‘credit and obedience’ is only due to what we ‘necessarily conclude’ from the things that Scripture plainly delivers, not reason musing on things in general. The same applies to ‘tradition’, or the voice of the church: when we’re not sure what Scripture means by what it says, we listen to other Christians, and the judgement of the church in such cases does ‘over-rule all other inferior judgments whatsoever’ (to continue the Hooker quote above), but when we are sure what Scripture means, we maintain it even if the rest of the church contradicts this. This is what the Reformers called ‘private judgement’. No one needs an intermediary between himself and God’s word, and no one has the right to act as one. What the rest of the church believes about something when Scripture is silent, such as an ‘apostolic succession’ as essential for ministry, is not seen as having any authority, and must always remain optional.