Behold, how good and how pleasant it is for brethren to dwell together in unity.
The writer of this psalm is posing a question regarding believers living together in unity and in doing so we as believers emulate the unity of the Godhead. This can be achieved by believers yielding control to the indwelling Holy Spirit who is God. Dwelling together expresses love for self, God and one another and bring into focus John 17 where Jesus prayed for His followers would be established in love, in holiness and unity.
Another school of thought is that the Godhead there is complete unity and harmony and this is expressed in God's work in the lives of humanity. Let's look at the Godhead, God the Father gave the Son and the Son gave His life redeeming man back to God. God the Holy Spirit dwells in every believer as our guide, teacher and protector while here on earth. There is complete harmony in the Godhead and this same harmony should exist among believers regardless of whom or where the believer may be.
There is a phrase that asks can two walk together unless they agree; the answer is no because it represents disharmony. When the church came together and prayed for Peter while he was in prison the church was on one accord just as it was on the Day of Pentecost. What this all says is that when believers come together in unity then the Spirit of God will be in the midst.
There is unity in the Godhead and among the brethren.
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