Now I beseech you, brethren, by the name of our Lord Jesus Christ, that you all speak the same thing, and that there be no divisions among you; but that you be perfectly joined together in the same mind and in the same judgment.
All Commentaries on 1 Corinthians 1:10 Go To 1 Corinthians 1
John Chrysostom
AD 407
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.