I recently, for a couple weeks, experienced a really angry mood.  I mean really angry, angry at myself, at my ex-wife, at my doctors, at a nearby hospital, and last but not least, very angry at God. I apologize if this offends any Muslims.  As a western Sufi mureed I have great respect for the faith and would never intentionally disrespect the faith.  In fact a great sorrow of my old age is not being literate in Arabic, which would allow me to read the Holy Quran as originally written from the oral tradition. Allah does not mind anger if the prayer is sincere.