Then only will there be Christian unity among us, when there is not merely a good agreement as to doctrine, but we are also in harmony in our affectiotions and dispositions, and thus in all respects of one mind. Thus Luke bears witness to believers in the early Church (Acts 4:32) that they had one heart and one soul. And without a doubt this will be found whenever the Spirit of Christ reigns.
John Calvin,
Commentary on 1 Corinthians, 1:10