I have no personal experience with the Amish, but as I said above, I have friends who have lived and worked alongside them in Pennsylvania and Ohio, one being a direct neighbor and another married to a girl from a shunned family. According to what I've been told and have read, they are often very legalistic (i.e. to the point of often being identified with Pelagianism), especially the Old Order.
But I recently came across this video (link is below) produced by the BBC, and while I was a bit frustrated with the way certain questions were phrased for the sake of undermining religious beliefs, biblical values, and traditional gender roles (what else can you expect from the BBC?), I was still very well-pleased with the production. Clearly, the couple in this film (David and Miriam Lapp) have made a theological break with the Amish church and have personally embraced evangelicalism, though at the same time remaining in the Amish church and retaining their Amish cultural identity. At least for this family, it was evident that all joy and happiness is found only through the Lord Jesus Christ and fellowship with one another, and that it was ONLY through faith in Christ that one could obtain personal salvation. David and Miriam likewise seem to be an incredible Christian model of how to be a husband and wife, father and mother--serving and being served in all humility according to the Scriptures, with a life centered on the Word of God and love for Christ and his people. (Plus, they have the most adorable little children!)
What I want to know is not whether there are more people like the Lapp family (because I know that there are according to what I've been told by personal acquaintances), but whether there are whole Amish communities who have abandoned the the theological Anabaptist/Amish tradition altogether and embraced evangelicalism or even Reformed Theology, while at the same time retaining their cultural identity as Amish. This can really only be known from people who live with, work with, or have personal dealing with the Amish since they are often extremely seclusive in regards to filming and publishing material. So if anyone out there has info, please let me know!
"Amish: A Secret Life"
https://youtu.be/HtNXvE_rLoE