In my mind anger is based in fear. Fear of loss, fear of judgement, fear of betrayal and many others. It is the root of human weakness and it is how we corrupt our minds. This corruption holds us back in life, but when we learn to release our fears and become masters of our own mind we hold back fear by taking it's power away.
Napoleon Hill said in Outwitting the Devil:
"I know nothing about any form of prayer which can be induced to work favorably in a mind that is colored, in the slightest degree, by fear."
The way I interpret that statement is as follows - Prayer is intention that is put forth into the universe and this intention is weakened by fear.
Any rate that is my thought on the subject.