...all that really exists is in and of God, and manifests His love.

Divine Love is infinite. Therefore all that really exists is in and of God, and manifests His love. 
“Thou shalt have no other gods before me.” (Exodus xx. 3.) The First Commandment is my favorite text. It demonstrates Christian Science. It inculcates the tri-unity of God, Spirit, Mind; it signifies that man shall have no other spirit or mind but God, eternal good, and that all men shall have one Mind. The divine Principle of the First Commandment bases the Science of being, by which man demonstrates health, holiness, and life eternal. One infinite God, good, unifies men and nations; constitutes the brotherhood of man; ends wars; fulfils the Scripture, “Love thy neighbor as thyself;” annihilates pagan and Christian idolatry, — whatever is wrong in social, civil, criminal, political, and religious codes; equalizes the sexes; annuls the curse on man, and leaves nothing that can sin, suffer, be punished or destroyed.
SH 340:12-29 Divine

From Concord Express - A Christian Science Study Resource: The King James Version of the Bible and Mary Baker Eddy's published writings

All men shall have one Mind.