This passage is a foundational truth, principles of life for every believer. This is how we are to live, this is what distinguishes us from the world, from the heathens, the pagans; the unsaved whatever you want to call it. This is the distinct behavior of those who truly belong to Christ, this is how we are separated from the world, by our love.
It is easy to make over the the outward appearance, what is on the surface, but sometimes this leads us to ignore what is under the surface, especially when what is under the surface is uncomfortable and even painful. God knows we have a deeper problem, and therefore he has given us a more lasting solution. We have a sin problem—painful to admit, yet impossible to manage on our own. We need help. When we acknowledge we need help and admit our inadequacy, we are drawn closer to God. We need his grace, love and tender forgiveness.