Because God calls us to live a peculiar life.
Here are the places I have found where God speaks specifically about living the peculiar life.
Why christians should be peculiar
As Christians we claim to structure our lives around the teaching of the Bible. This is distinctly different from our secular counterparts. Our philosophy isfundamentally different. Philosophy is that thing on which one builds all ones understanding of, and which is used to instruct our prosecution of our lives. Thus a different philosophy will inevitably lead to different choices being made, and a visibly different life being lived. Those very differences appear peculiar to those around us.
The Bible may not provide an exhaustive textbook for every discipline. It is however the basis, the very source of our philosophy, and that which guides and instructs us. As such it speaks definitively to every single area of life, in ways which are surprising to most in their breadth and depth.
It is our goal to seek out those ideas and philosophies which may seem at first to be peculiar and apply them to each and every area of our lives, seeking the truth and not selling it out, but rather applying it faithfully to each and every area.