How can atheistic criticism of historic faiths and religions contribute to a better understanding of religion?

Nobody can have a meaningful examination of a common point of view in a mutual admiration society where everyone sits around saying "You're so right!" on any point raised. The opposing view is necessary to point out errors and inconsistencies that must be explained, proven right or wrong, or accepted.
The problem that prevents many of the religious from considering the atheists points are that they may lead to the understanding that religion is not right - this is viewed as undesirable to the religious.