Traditionally Christians emphasized such moral principles as duty, discipline, thrift and hard work.

such...as...  和  such as ...  都可以用来表示“列举”（不完全列举）。其格式是：

1. such + 复数名词（总体概念）+ as ...（个体概念）

2. 复数名词（总体概念）+ such as...（个体概念）

网友的句子，还可以用第2种格式表达：

Traditionally Christians emphasized moral principles  such as duty, discipline, thrift and hard work.