1. Do I love the world? Do I love that which is in and of the world? Are my loves any different from those of the unbelievers around me?
2. Do I take sinful desires and actions seriously? Do I see how opposed they are to the holiness and will of God? Do I smell the shed blood of Christ or hear eternal judgment pronounced as I see sin committed? Is what I am willing to accept as allowable for life and entertainment different than that of unbelievers around me?
3. Do I arrange my life in such a way that I am not spending my energies fulfilling fleshly desires, chasing after what I see, and finding my identity in what I possess? Are my priorities distinct from unbelievers around me?
Those are not controversial questions, not even for many evangelicals, let alone fundamentalists. This is the type of definition of worldliness that you will find in C. J. Mahaney's book on worldliness, in R. Kent Hughes's book on worldliness, or in a book John MacArthur wrote years ago. Historically, those questions have not been how fundamentalists have talked about worldliness or personal separation. Don't get me wrong. I think they are very good questions to ask and for which to have good answers.
If worldliness is what those two articles (Johnson's and Edwards's) are about, then Johnson is wrong about evangelicals not writing about it -- that's exactly what they write about. What they don't write about, and what fundamentalists have historically emphasized, many times will be labeled "externalism."
I do think that there is a worldly heart, but I've written many times before about the myth of internal-only worldliness. There is a problem with external worldliness too. The heart problem is an issue, but there is also the problem of what we look like, what we watch, what we listen to, how we act, and what we say. Paul wrote, "Be not conformed to this world." "Conformed" is an external concept.
It is true that someone can externally not be worldly and then be worldly in the heart. It's true. However, that doesn't mean that someone is not worldly if he claims not to be worldly in the heart (because we don't really know what he is in his heart), but he is in fact worldly on the outside. The new emphasis on heart worldliness can be and might be a diversion from external worldliness. I think and believe that it is. There could be many reasons not to talk about external worldliness, worldliness on the outside, but again I think and believe that fear is the biggest reason.
What are people afraid of? They don't want to be marginalized. They don't want to be labeled a legalist or a Pharisee. They don't want to lose people who want to fit into the world, and the externals are mainly where people fit in. This affects church growth, so there is size and budget that are at stake too.
In addition to fear, they actually do love the world. You can love the world and say that loving the world is just on the inside. That way you can say that you don't love it, when you actually do. How can you tell? The music, the dress, the attitudes, the language, the entertainment.
Because a Christian is sacred and his body is the temple of the Holy Spirit, he can't associate with external things that clash with God. Christians are in the world, but not of the world. Today's evangelicals and even fundamentalists joke about some of the trends that fundamentalists at one time stood against. However, Spurgeon believed that if you were someone who regularly attended the theatre, you probably weren't saved. The Puritan Vincent Alsop preached the sermon, "The Sinfulness of Strange Apparel." Part of personal holiness, biblical separation, has been to avoid ungodly associations in the world. Not to do so had been worldliness. It still is.