When I do Salah (formal prayers) or intend to do good deeds I often get very evil thoughts in my mind. When I concentrate in Salah, and try to focus on the meaning of the words, evil thoughts enter my mind, which make evil suggestions about everything including Allah. I feel very frustrated and angry about this. I know that none forgives sins except Allah alone, but because of my thoughts I feel that there is nothing worse than to have evil thoughts about Allah. After Salah I ask Allah's forgiveness, but feel very bad because I want to stop these evil thoughts, but I can't stop them. These thoughts spoil my enjoyment of Salah, and also make me feel as though I am doomed. Please advise me.