Paul wants us to “maintain the unity of the Spirit in the bond of peace.” (Ephesians 4: 3) Again, he implies here that sometimes we do not have unity in the body of Christ as we ought.
Of course, this should be painfully obvious to us today. We have a myriad of denominations in the greater Church, each with some crucial (or worse) miniscule difference from another. The Roman Catholic church maintains that the greatest sin is this division in the Body of Christ, the true Church. This is hard to argue against. I know Paul agrees.
“There is one body and one Spirit — just as you are called to the one hope that belongs to your call — one Lord, one faith, one baptism, one God and Father of all, who is over all and in all.” (Ephesians 4: 4 – 6)
The aim, the upward call of God is that “we all attain to the unity of the faith and of the knowledge of the Son of God, to mature manhood, to the measure of the stature of the fullness of Christ.” (Ephesians 4: 13)