May God who gives patience, steadiness, and encouragement help you to live in complete harmony with each other—each with the attitude of Christ toward the other. And then all of us can praise the Lord together with one voice, giving glory to God, the Father of our Lord Jesus Christ. (Romans 15:5-6)
Harmony is not achieved by our own merits, for no set of humans actually 'live in harmony' with another set of humans without some form of conflict from time to time. As long as atoms keep crashing together, there will be some form of conflict, BUT...God can bring patience where conflict seems to abound, steadiness where the foundation has begun to crumble, and tremendous encouragement to keep moving toward agreement and peace.
How is complete harmony ever going to happen? Those who have embraced Christ as their Lord and Savior will be at the forefront of peaceful actions. They will bring a steadfastness into the most difficult of circumstances - a peace and assurance that stands when all else is crumbling in around them. What will this peace and assurance serve to do when chaos abounds? It brings encouragement that there is a way out of the hardness of the moment.
Where does harmony begin? It begins within our own heart first, then it begins to affect those around us. Are you are harmony with God? What does a heart in harmony with God look like? If you are making choices that are in accord with the truths he lays out in scripture, you are on the right path. If you have a desire to see his will done more than your own, you are on the right course. In other words, our actions begin to reflect less of a 'me, me, me' attitude and more of a 'whatever your will is, Lord' purpose.
Some would believe harmony is the absence of chaos entirely, but we grow best within a certain amount of chaos. Harmony is merely a 'congruence' of the parts - not that all parts are the same, but that they 'fit' and 'work' together. Harmony is going to be the place where we see 'conflict' and 'chaos' leading us onward to what is true and lasting positive change. The challenge is there, but we must not bow to the desire to let it defeat God's desire to see patience, steadiness, and encouragement developed within our hearts. Just sayin!