"It is possible to agree on a form of words but still harbor dissent, which is why Paul speaks the way he does here. It is also possible to share the same opinion with someone but not the same feelings. For example, it is possible to be united in faith without being united in love. This is why Paul says that we must be united both in mind and in judgment."
St. John Chrysostom, Homilies on the Epistles of Paul to the Corinthians, 3.2