In John 17 we see that Jesus wants His followers to be perfectly one with each other. He wants His Church to be perfectly one. As long as we are in different denominations, we are not perfectly one, because we are still divided. As long as we are divided in different denominations, we pain the heart of Jesus.
Ask yourself this question: What am I doing to bring about the unity of all Christian denominations?
Many Christians seem to be content with the divisions in the Church. Or they seem to think that there is nothing that can be done about those divisions. Or they think that their separation from all other denominations is required by verses such as 2 Corinthians 6:17, where St. Paul writes, "Therefore, come out from their midst and be separate, says the Lord."
But St. Paul is saying there not to be yoked together with *unbelievers*; he is not contradicting Jesus's prayer in John 17. St. Paul himself wrote in his first letter to the Corinthians, "Now I exhort you, brethren, by the name of our Lord Jesus Christ, that you all agree, and there be no divisions among you, but you be made complete in the same mind and in the same judgment." (1 Cor 1:10)
What can you do to help bring about the unity of the Church, a unity that Christ deeply desires His Church to have? You can pray for the unity of the Church. Meditate on John 17 until Christ's desire for the unity of His Church becomes a burning passion in your own heart. Commit yourself to dialogue with Christians in other denominations about ways to reconcile the various divisions in the Church. Listen carefully and sincerely to the positions, beliefs, objections and perspectives of others, and learn them. Call the attention of other Christians to the disparity between the present divided state of the Church and Jesus's prayer for unity in John 17. Don't give up when you don't see progress, or you are rebuffed, or ignored. If you see that you were wrong, admit it and embrace the truth. Don't cling to a position simply because you have believed it a long time and it brings you comfort or security. The truth must be more valuable to you than security. Don't let your dialogue turn into a competition, because that obscures truth as the goal of our dialogue. And if the goal of truth is obscured, then reconciliation cannot occur. As Peter Kreeft says, "So how do we get reunion? By finding the truth. Truth is the only possible basis for reunion." Continue to pray and reach across the fences that divide us, committed to doing whatever is in your power to reconcile all Christians in unity. Network with other Christians (such as myself!) who are making efforts to bring about Christian unity. Read and discuss what it means to be in perfect unity. Without some conception of a goal, how can one pursue that goal? Various thoughts of mine on achieving the goal of church unity can be found here.
"Blessed are the peacemakers, for they shall be called sons of God." - Matthew 5:9
"Let unity, the greatest good of all goods, be your preoccupation." - St. Ignatius of Antioch (Letter to St. Polycarp)