Fulfil ye my joy - Fill up my joy so that nothing shall be wanting to complete it. This, he says, would be done by their union, zeal, and humility; compare John 3:29.
That ye be like-minded - Greek That ye think the same thing; see the notes at 2 Corinthians 13:11. Perfect unity of sentiment, opinion, and plan would be desirable if it could be attained. It may be, so far as to prevent discord, schism, contention and strife in the church, and so that Christians may be harmonious in promoting the same great work - the salvation of souls.
Having the same love - Love to the same objects, and the same love one for another. Though their opinions might differ on some points, yet they might be united in love; see the notes at 1 Corinthians 1:10.
Being of one accord - σύμψυχοι sumpsuchoi - of one soul; having your souls joined together. The word used here does not occur elsewhere in the New Testament. It means a union of soul; or an acting together as if but one soul actuated them.
Of one mind - Greek “Thinking the same thing.” The apostle here uses a great variety of expressions to denote the same thing. The object which he aimed at was union of heart, of feeling, of plan, of purpose. He wished them to avoid all divisions and strifes; and to show the power of religion by being united in the common cause. Probably there is no single thing so much insisted on in the New Testament as the importance of harmony among Christians. Now, there is almost nothing so little known; but if it prevailed, the world would soon be converted to God; compare the notes at John 17:21 - or see the text itself without the notes.