He is, as you say, too final and too dogmatic. This is at once his weakness and his strength: his weakness, because it limits his own spiritual receptivity; his strength, because it focusses his power in dealing with materialistic minds.
A more spiritually true perspective in his communications would rule out half the souls to whom his appeal is made.
_Stainton Moses has also progressed beyond the Imperator influence, and this is why the communications between them had become so clogged and so liable to error._
S. M. could not switch on to the old wires, as in the days when his horizon was bounded by them. This accounts, I see, for much of the misconception and apparent inconsistency of the remarks made through Mrs Piper, but it was very disheartening for the investigator as time went on and the "Light" became more and more clouded. Then there was the additional fact to be faced, that Mrs Piper herself became, psychically rather than physically, exhausted, and less able to be used from this side.
Now I see you want to know about Frank Strong, and what he said about sin existing only on your plane, and how inconsistent this was with the previous teachings of Stainton Moses, who was supposed to be speaking through Frank's assistance.
It is so difficult to explain everything in black and white when there are so many shades of grey, so many degrees and amounts to be considered. It is like a question in mechanics.
With increased momentum you get an increased rate as multiplied by space. I am not an expert, but this is practically true. In the same way, spiritual perception acts with increased momentum.
All sin is failure in spiritual perception. Spiritual perception corresponds with the momentum of a falling body in mechanics. Only in Divine mechanics it is a _rising_ body; but the same law holds good.
You say truly that an action can only be called sinful when the sinner knows the higher and deliberately turns to the lower.
That is true; but it is only half a truth. It is still the _lack of knowledge_ that causes sin. With the fulness of knowledge of the higher (only another way of putting fulness of spiritual perception) _must_ come the righteousness of life.
It is the broken gleams, the little knowledge, which is truly a dangerous thing, for it brings responsibility, and therefore the capacity for sinning. Yet the _choice_ between good and evil fully made, is the schoolmaster to bring us to the full realisation of our nature as Sons of God.