—1 Peter 3:8-9 (NASB)
By definition a "commandment" is actually an obligation of a contract — a "covenant" with God which spells out what you have to do to successfully keep your end of the agreement. There then seem to be a lot of additional rules in the Bible which serve as examples defining how to keep those commandments. When Jesus says in the New Testament, "A new commandment I give you, that you love one another", (John 13:34) He is providing the basic contractual obligation we must adhere to in order to maintain the New Covenant, not just giving us advice. And there are a lot of additional verses like these in Peter which describe how to go about fulfilling that obligation. As you may have noticed, everything listed here pertains to the quality of our personal relationships with others.
I wonder at times if we haven't forgotten that a Christian is supposed to be "different" from everyone else. Even if you're not a Christian yourself you're supposed to be able to detect that there's something "different" about someone who is. I'm using "different" in the best sense possible, but often I've encountered Christians in the workplace and in the course of life who have been labeled "different" in the sense they can't be trusted, they misbehave egregiously, or are simply the worst examples of what they claim is Christianity. I've been in a couple of environments where the so-called, publicly-professing "Christians" were so embarrassingly wicked and destructive that I would withdraw in order not to be identified with them.
But just how much trouble and undeserved slander do you think will actually come your way if you truly put these things into practice to the degree that they are visibly evident to everyone around us: "harmonious, sympathetic, brotherly, kindhearted, and humble in spirit"? And if our relationships were characterized by these qualities, then when the odd insult came our way but we handled it according to this standard, it would reinforce a very powerful personal testimony that there is something truly "different" about Christians. It's not a pie-in-the-sky dream; Peter says that this kind of behavior is "the very purpose" for which we "were called". We're supposed to act this way.
The most notable negative example out there right now is a church group who is going to the funerals of soldiers who've died in Iraq and Afghanistan where they don't merely loudly protest during the time of a family's grief, but make the bold statements that this is all deserved as a result of God's judgment. There's nothing "harmonious, sympathetic, brotherly, kindhearted" or "humble in spirit" about these people. And there's nothing in their actions that's in keeping with the commandment of the New Covenant so as to maintain their obligation of love. How we treat people carries with it greater ramifications than merely being polite or civil, but defines the very Christianity we purport to cling to.†††