Unity involves obedience to Jesus Christ.
The whole essence of a Christian is that we follow Jesus Christ, and this involves obedience:-
.. the sheep listen to his voice. He calls his own sheep by name and leads them out. When he has brought out all his own, he goes on ahead of them, and his sheep follow him because they know his voice.”
A Christian knows where to find the voice of Jesus, which is in the Bible!
What is the Bible? God’s Word, the Truth.
Even in Jesus’ prayer in John 17 we learn that the disciples ‘have obeyed your word.’
I have revealed you to those whom you gave me out of the world.
They were yours; you gave them to me and they have obeyed your word.
Now they know that everything you have given me comes from you.
For I gave them the words you gave me and they accepted them.
They knew with certainty that I came from you, and they believed that you sent me.
In John 8 He tells us that being a disciple involves knowing and holding onto all the teachings of Jesus.
In other words a Christian is someone who knows and obeys His teachings:
Jesus said, ‘If you hold to my teaching, you are really my disciples. Then you will know the truth, and the truth will set you free.’”
Then in this same teaching session, Jesus explains why people don’t accept His teachings.
It is because they don’t belong to God:
Why is my language not clear to you? Because you are unable to hear what I say.
You belong to your father, the devil, and you want to carry out your father’s desire …
He who belongs to God hears what God says.
The reason you do not hear is that you do not belong to God.’”
Someone who doesn’t belong to God, doesn’t understand God’s teachings.
They don’t want to obey the Lord’s commands, therefore they are not a Christian.
But someone who knows and loves Jesus Christ, will have a desire to understand, and submit to God’s Truth, the Bible:
If you love me, you will obey my commandments.
And I will ask the Father, and he will give you another Helper who will be with you forever. That is the Spirit of truth …
A person who doesn’t love me doesn’t do what I say.”
John 14:15-17 & 24 (God’s Word translation)
Paul commands the Christians at Thessalonica to:
.. stand firm and hold to the teachings we passed on to you, whether by word of mouth or by letter.”
2 Thessalonians 2:13-15
Hold onto the teachings.
These teachings are not something to be casually tossed aside for the sake of unity.
In fact we unite around these teachings.
Unity is important among Christians, and Christians are those who have a desire to obey all of God’s teachings.
Not so as to work for their salvation, no, they are saved by faith in the sacrifice of Jesus Christ, and therefore they now want to obey Him as Lord and Saviour.
So unity is being united around Jesus’ teachings.