Amishman David Wagler shares some thoughts on non-conformity, from the pages of Family Life:
"The banner verse is found in Romans 12:2, "And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect will of God." There are two schools of thought in the interpreting of this verse, and it makes a big difference in our lives and conduct which of the two we accept.
The widely-accepted view is to focus on the renewing of our minds. If the heart is right and we accept Christ as our Saviour, then we are a child of God. This is the standard evangelical teaching. Those who take this position believe in living a good moral life but see nothing wrong in dressing like the world as long as they can "praise God and give Him the glory."
The Amish and other plain groups, however, interpret this verse in Romans 12 to mean that Christians are to be different from the world in every part of their lives–nonconformed in thoughts, appearance, and in actions. We are not to look to the styles and fashions of the world for our pattern, but be conformed instead to God's standards as interpreted by the church. This will result in distinctive attire and a simple lifestyle.
We understand, of course, that the only way we can live a truly nonconformed life in God's will is by the renewing of our minds in Christian faith. That is the only formula by which we can grasp the need for the plain and simple life, separated from the ways of this world…"
(Family Life, "Now That I Think of It: Cousins in Nonconformity", March 1996)