"Evangelical" is a term that has come to mean different things in different places. Originally it meant "holding to the Gospel" (as opposed to 'liberal' theology). If you want an "official" definition, the most widely accepted one is the "Bebbington quadrilateral":
- The Bible: a particular respect for the Bible (e.g. all essential spiritual truth is to be found in its pages)
- The Cross: a focus on the atoning work of Christ on the cross
- Conversion: the belief that human beings need to be converted
- Activism: the belief that the gospel needs to be expressed in action
By this definition, you can find evangelical Christians in all denominations (even the Catholic Church!)
But then it gets more complicated.... in the USA, "evangelical" is a term that has become associated with white Republican voters. It's become politicised and even racialised. Presumably this is where the idea of "evangelical
ism" has come from - it's a term I've never heard used in the UK.
To me evangelicalism is any who are not part of Traditional Churches such as Anglican/Episcopalian, Catholic, Orthodox, Lutheran, Methodist, and I may be missing some.
So what term would you use for those people who fit the definition above but are members of 'traditional' denominations? We would call ourselves 'evangelical' - what would you call us?
"Sola Scriptura" is another much misunderstood term. It goes back to the Reformation, when Luther and other reformers were going back to the Bible and dismantling some of the extra church traditions that had grown up over the centuries. It doesn't actually mean "the Bible is our only authority" but "the Bible is our only
final authority". Against the Catholic teaching that the church has
equal authority with the Bible, Protestants believe that the Church must be
subject to the Bible. This doesn't rule out tradition altogether, but it puts it in its proper place.