I’ve learned through drawing and painting that art (at least in its more recent representational forms) is usually diminished when we devote too much time to “improving” the areas whose actual contours we don’t understand very well.  All this effort tends to show, and the net effect is typically to direct people’s attention to areas that don’t have much to do with what would actually render the artwork most compelling or memorable.
 
I’ve found it’s better to just fade out the elements that I don’t have as good a grasp of—as well as those I just don’t find especially interesting.  Since the human brain can do quite a bit with small but telling bits of information, the results can be a lot more powerful.  For example, in doing a portrait, if you start with the eyes and render them with conviction, you’ve pretty well captured a person’s essence.  Parts like elbows or toes don’t tell us a whole lot.

I believe that when followers who outlive the great messengers begin proselytizing unsupervised on their own, they tend to spend too much time addressing issues their visionary leader said little or nothing about, and too much effort converting his messages into more traditional religious institutions, which purport to provide necessary direction in all areas of life.  

One illustration:  I don’t mean to pick on any one religion, but certain Islamic rules regarding the role of women have been found to be based not on the writings of the Prophet Muhammed, but simply on Bedouin tribal customs.
 
If educated modern-day adherents of all the historic faiths could perform more rigorous scholarly re-evaluations of their traditionally-accepted beliefs, trimming them down to just the ones that are the most reliably traceable to the words of the messengers themselves, I think the world would gain a more compelling and useful distillation of each individual religion’s most precious essence.
 
If this were to occur, I believe we’d also find numerous areas where one religion has relatively little insight to share, but another has a lot.  This could enable us to incorporate the best elements of all the world’s major religions into a blended whole that would be far more valuable than any one of them by itself.