Unity seems to come and go. Political alliances form and later fall apart. Friendships sour. Crises bring people together —until the danger is over. Human unity may at different times be more or less genuine—based on genuine goodness. But no foundation for real, lasting unity exists apart from an understanding of spiritual reality, because the material conception of existence is inherently divisive and self-destructive.
The concept of life as material, and of man as proceeding from matter, begets disunity, because it doesn't recognize God, immortal Spirit, as the only creator, as the one Mind, or Ego, the one Principle governing all. It is actually a misconception, which accepts instead the erroneous view that there are many minds, all revolving in their own diverse orbits. Yet Spirit is infinite; therefore Spirit is one, not many. Spirit is the only Mind, and this Mind is entirely good. Everything real has its source in God—emanates from Him, reflects Him, and is governed by Him. Man is God's expression, or image. Man therefore expresses the one Mind. Just as each ray of sunlight comes from the same sun as do the other rays, the real individuality of every one of us comes from God and manifests Him. This doesn't mean we're all identical to each other. It simply means that we all manifest the same Mind, the same Life, Love, and Soul through the endless variety of spiritual individuality.
Shortly before his crucifixion, Christ Jesus prayed for his disciples. While praying, he mentally reached out to the welfare of others beyond his immediate followers: "Neither pray I for these alone, but for them also which shall believe on me through their word; that they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us." John 17:20,21. Jesus embodied Christ, the divine image, or ideal, manifesting God's nature. In Christ, all being is one, because being emanates from the one Mind. To the degree that Christ is demonstrated through spiritual understanding, spiritual healing, and Christliness of character, humanity becomes one in Christ and the unity of Spirit becomes evident in human affairs.