When we actually know the truth the effect is healing. But when we admit something that is not completely true, our good intentions may fall short of the mark.
It is true that God is All and that man is His reflection. And it is true that "in him we live, and move, and have our being" (Acts 17:28). But it is untrue that God ever loses control of a single detail of the universe or that in His infinite consciousness there can be any sin, disease, discord, or death.
Now, one can express the truth by referring to its opposite, error. A statement that evil is nothing is another way of saying that God, good, is All. But if one declares the nothingness of evil while still beholding evil as a reality, he is not knowing the truth. A wishful effort to make evil go away cannot succeed unless the mental picture of evil is destroyed and replaced with the divine idea of God. In her book "Unity of Good," Mrs. Eddy says (p. 54), "To say there is a false claim, called sickness, is to admit all there is of sickness; for it is nothing but a false claim."