When we trusted Christ as our Savior, we were made one with him.  Through the Holy Spirit, we are in the body of Christ and we are members of one another, Rom 12:5; Eph 4:25.  So, without a doubt, there is union.  And that union is unbreakable.  We are sealed by the Holy Spirit, Eph 1:13, 4:30.  

But union is not unity.  Union is the act of uniting or joining two are more things into one.  In a marriage, there is a union.  The two become one flesh.  Unity, on the other hand, is a condition of harmony.  In Acts 1:14, those gathered in the upper room “all continued with one accord.”  That’s unity.  Contrast their unity with the discord that was among the Corinthians.  

There were contentions in the church at Corinth which affected their unity, 1 Cor 1:11.  Paul wrote, “Now I beseech you, brethren, by the name of our Lord Jesus Christ, that ye all speak the same thing, and that there be no divisions among you; but that ye be perfectly joined together in the same mind and in the same judgment,” 1 Cor 1:10.

So, while we need not endeavor to keep the union of the Spirit, we must endeavor to keep the unityof the Spirit.  

God gives us two principle tools to keep the unity of the Spirit.  The first is the bond of peace, Eph 4:3.  The second is “charity, which is the bond of perfectness,” Col 3:14.

Through the bond of peace.  Eph 4:3 – When two or more people are at peace with each other, there is unity.  And when they are not at peace, there is tension and war.  The Biblical way to maintain the peace is through reconciliation.  Look at Rom 5:1, 10.  “We have peace with God through our Lord Jesus Christ.”  “When we were enemies, we were reconciled to God by the death of his Son.”

I am one with you, but I don’t have to be at peace with you.  You and I can be really opposed to each other.  When you get cross ways with someone, sit down, discuss your differences, and reconcile.  When something goes out of kilter in my relationships, the first thing I do is ask God to search my heart and try my thoughts.  What part do I have in this problem?  Once I have gone through this, then I sit down with the other person to discuss how we got here and how we can reconcile and keep from going here again.  Once you reconcile, you are at peace and the unity is kept.  The unity is often stronger because of the reconciliation.

Through the bond of charity.  In Col 3:14, Paul wrote, “And above all these things put on charity, which is the bond of perfectness.”  Charity is described in 1 Cor 13:1-8 and is essentially the fulfillment on the Lord’s command in Jn 13:34-35.  When we love one another as Christ loves us, all men know that we are his disciples.  We are unique.

No matter what, when you sense that the unity is being strained remember to love one another, and demonstrate that love.  You must know that the devil wants discord in the body of Christ.  One of the greatest defenses against discord is charity.  Charity never faileth.  It beareth all things and endureth all things.  ALL things.  

Conclusion: whatever you do, endeavor to keep the unity of the Spirit.  When you see any strain in your relationships, reconcile with one another and love one another.  This will keep the unity.  And it will add to the joy of your relationships.  The first three manifestations of the fruit of the Spirit are love, joy, and peace.  When love and peace prevail in your relationships, joy naturally follows.