Other sheep I have which are not of this fold; them also I must bring, and they will hear My voice; and there will be one flock and one shepherd.
– John 10:16 –
Christians are united to one another because of their common unity with the Good Shepherd, Jesus Christ. We are one flock because we belong to Him. Our unity must be founded upon this reality. Our creeds do not make us one. Our church buildings and activities do not make us one. Our good works do not make us one. The Holy Spirit makes us one. He makes us one by joining us to Jesus Christ.
Christian unity is first and foremost a work of God, not a work of men. It is a byproduct of our salvation, not a way to earn salvation. The Lord creates our unity and gives unity. We merely receive and preserve it. Understanding this is important because it motivates us to pray and depend upon God rather than ourselves. Understanding the Lord as the creator and giver of unity urges us to preserve the unity of the church because it comes from Him and not men. The Good Shepherd calls us from every tribe and tongue, gives us ears to hear His voice, and makes us His flock. This is how unity is made. Praise the Lord!