This Psalm expresses the same spiritual truth as John 17, where Jesus prayed that His followers would be characterized by love,holiness and unity.
Deep love for God and for one another, along with spiritual growth based on truth of God's word, will allow people to experience God's presence in a powerful way.
This psalms uses two analogies to describe godly unity, and its effects within a group of believers.
[1] There is the image of the image poured on Aron's head being like unity.
The psalmist speaking of God's anointing -his commissioning blessing and empowerment. The psalmist make a direct like between unity among God's people and the experience of God's blessing and power among them.
This does not mean that whenever people are unified in purpose that God's blessing and power will automatically be present (because their purpose may be wrong).
However, it does mean in order for God's blessing and power to remain on a congregation of believers, they must be unified in heart and godly purpose.
[2] There's also the image of dew on the mountain being like unity. Here the psalmist is speaking of refreshing quality of unity. Most of us have felt the heaviness of an atmosphere where there is tension and disunity. But unity is an uplifting and inspiring quality that is present among any group of godly people who are truly ready to experience God's blessing.
[NIV Study Edition Bible.]
Stay Bless.
Shalom.
