A fallible being is in no position to say what a supreme being would or would not do. Moreover, a supreme being is under no obligation to be truthful to its creations.
You said it yourself... God works in mysterious ways. How can you be certain that deception is not one of those mysterious ways in which God works? If God can ordain the killing of infants to achieve a purpose then surely God can ordain lies to achieve a purpose.
It seems to me that if humans are the creations of a god then it may have given humans the ability to reason so that we may discern bad teachings from good teachings even when the teachings are said to be from the highest of authorities.









