Popular consciousness says: When conscience speaks, it is God speaking in the soul. The highest spiritual consciousness says that when conscience speaks, it is truly the cosmic Spirit speaking. And spiritual science brings out the connection between conscience and the greatest event in the evolution of mankind, the Christ-Event. Hence it is not surprising that conscience has thereby been ennobled and raised to a higher sphere. When we hear that something has been done for reasons of conscience, we feel that conscience is regarded as one of the most important possessions of mankind.
Thus we can see how natural and right it is for the human heart to speak of conscience as “God in man”.
[…] conscience is the highest voice in our inward life. On this account, also, we are aware that our dignity as human beings is inseparable from conscience. We are human beings because we have an ego-consciousness; and the conscience we have at our side is also at the side of our ego. Thus we look on conscience as a most sacred individual possession, inviolable by the external world, whose voice enables us to determine our direction and our goal. When conscience speaks, no other voice may intrude.
So it is that on one side conscience ensures our connection with the primordial power of the world and on the other guarantees the fact that in our inmost self we have something like a drop flowing from the Godhead. And man can know: When conscience speaks in him, it is a God speaking.
Source: Rudolf Steiner – GA 59 – Metamorphoses of the Soul 2: Lecture 8: Human Conscience – Berlin, 5th May 1910
Translated by Charles Davy and Christian von Arnim