-> The guy whose central examples of religion are Pope Francis and the Dalai Lama is probably going to have a different perception of religion than the guy whose central examples are Torquemada and Fred Phelps. If you convert someone from the first kind of person to the second kind of person, you've gone most of the way to making them an atheist.
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-> More important, if you convert a culture from thinking in the first type of way to thinking in the second type of way, then religious people will be unpopular and anyone trying to make a religious argument will have to spend the first five minutes of their speech explaining how they're not Fred Phelps, honest, and no, they don't picket any funerals. After all that time spent apologizing and defending themselves and distancing themselves from other religious people, they're not likely to be able to make a very rousing argument for religion.