Sufism is a WAY of being religious. For sure. A very worthwhile study. As for conversion: life changing, viewpoint altering experiences, while not "common" are familiar to all races, creeds and tribes. The Buddha under the Bo Tree, for example. I wasn't trying to be mutually exclusive but I was speaking from personal experience. I can readily relate to similar profound experiences of other. There are many, many points in common to each.

The other point I attempted to make was that we cannot judge a work of art or a good deed by the character of the person who does the art of performs the deed. And, one should always be careful in judging someone without really knowing or understanding the context of their life and historical situation. Each age, each era has its own standard of truth and general idea of what is right and wrong. Some of these standards appear to be universal and timeless e.g. it is wrong to murder. Others, like polygamy are more nebulous or have the weight of history behind it. Judge "Amazing Grace" for it's internal logic, its own beauty. If it doesn't speak to you try "Papa's Got a Brand New Bag"! And don't be afraid to appreciate something just because the originator may have a skeleton or two in the closet.