“The glory which You have given Me I have given to them, that they may be one, just as We are one; I in them and You in Me, that they may be perfected in unity, so that the world may know that You sent Me, and loved them, even as You have loved Me” (John 17:22–23).
These two verses are part of the prayer that Jesus had with the disciples right before His death and resurrection. His prayer was for the oneness of all believers and yet when we read the epistles of the New Testament, we see that the churches already had problems of division.
In the first letter to the church in Corinth Paul relates division with immaturity, and one of the main emphasis of his letter was to solve the problem of division in the church. “And I, brethren, could not speak to you as to spiritual men, but as to men of flesh, as to infants in Christ. I gave you milk to drink, not solid food; for you were not yet able to receive it. Indeed, even now you are not yet able, for you are still fleshly. For since there is jealousy and strife among you, are you not fleshly, and are you not walking like mere men?” (1 Corinthians 3:1–3, NASB95)
1 Corinthians 3:4-11
Ephesians 4:11-16; 29-32