Tells you something is God's will or from God, check with God yourself. Listen to your conscience, not your emotions. Especially if your emotions are not within reason.
And where is it written that you can't say true things about religion? If a part of one's religious beliefs is wrong, then is it not our duty to enlighten that one? I know you shouldn't say anything bad about God. But you can. It's between you and God. If you believe in God, you would think this way. Why is the hand of man interfering in God's business?
Muhammad, please tell these people, who use God's name without knowing God, that God is real. Then let us see how they behave.