This really shouldn't be listed as one item of the thesis because, in my uncertain view, it under-minds most of what is wrong with Evangelicalism.
I will try to be concise as I explain my view and then give practical examples how this works out in real life.
Of course, there is a dualism in the way God had created the universe. There's the physical realm and the spiritual. The Platonic take on this (as well as others such as Zoroaster of Persia) is simply, the true reality is in the spiritual realm (thus Plato pointing up in the painting by Raphael). The physical world, according to Plato, was inferior and only a shadow of the true reality. Zoroaster and others go as far as saying that the physical world is not just inferior, but evil (as did many of the Christian Gnostics).
So, when you have this unhealthy view, that this physical world is insignificant, if not evil (many Christians talk about "worldly views vs godly views" thus implying that this physical world is slightly evil). So, this kind of thinking has a profound effect on how you live and think.
In my uncertain, humble opinion the Dark Ages were completely the result of Platonic Dualism within the Church. In today's time, the Taliban think in extremely dualistic terms (and I've had the opportunity to spend time with pro-Taliban people in NW Pakistan). Therefore, for them to blow up a nursery school (thus killing 50 pre-schoolers) is good if it accomplishes some spiritual purpose because the spiritual is so much more important than the physical realm.
If Evangelicals were in total power, as the Medieval Church was, we would now be in another Dark Ages. There is a micro-dark ages happening within Evangelicalism as we speak (in my uncertain, humble opinion).
So, how does this translate into Evangelicalism?
According to the Platonic-Christian Dualistic view, the following things do not matter:
The physical brain
Human history and the study of it
The role and influence of culture (or the study of, such as anthropology)
Laws of physics, thus cause and effect
Paleontology (science in general)
All fine art that was created by non-Christians
Human physical needs, food, water, shelter and emotional needs
So, the practical working out of the above thinking is that Evangelicals become very superstitious. For any of life's events to have meaning, they must be directly tied to the spiritual world. Grand ma didn't get better because of smart people using the laws (which God created, by the way) of biology of disease and medicine, but because an angel came into her room and touched her.
The car wreck that killed my child (speaking figuratively here) wasn't caused by them driving 60 mph on an icy road while texting their friend (and Newton's laws of centrifugal force and the coefficient of friction), but by God doing it deliberately to teach me patience or to trust Him . . . or possibly by Satan to try and disrupt my great ministry.
Here is another very earthy (pun intended) example and it is a good one because it involves my old Evangelical church and my new church. I can juxtapose one over the other for contrast.
My new church does a dinner for the homeless every Sunday afternoon at their church annex. It is an ecumenical event involving many churches in our town. At one point my old church and many other evangelical churches were involved with this event. A problem devolved when people from my old church (this was before I came here seven years ago) and other evangelical churches started giving the homeless people gospel tracts or trying, directly to evangelize the eaters.
My new church make a decision not to allow proselytizing during the dinner event because they did not want the homeless people to feel used (as a simple target for evangelism, like baiting a mouse trap with cheese).
If I heard the story correctly, my ex pastor (the one who came to my house to scream at me) thought that was inappropriate to "bar the gospel within the doors of a church." He led a revolt of the evangelical churches against my new church. None of them been involved since.
In their (Dualistic) thinking, even though these people were homeless, poor and hungry, food in their stomachs wouldn't do them any good. It had to be the gospel or nothing (thus the "spiritual" trumps the physical).
I think my new church has it right. Love is feeding the hungry . . . no strings attached . . . not using people . . . just a simple act of love for love's sake.