Considering I'm not a LDS member I thought I'd give it a shot. I'll leave the Polygamy comment alone because it really isn't relevant for fruitful discussion. The core of your question is related to doctrine and why someone would have a problem with LDS. It isn’t as much of a problem with LDS as it is a search for truth. Do all religions lead to the same place? It’s unfortunate that anyone who answers in the negative may well be ostracized for being narrow-minded and intolerant; or worse a “Conservative Christian”. The answer is NO! Not all religions lead to the same place. It is incorrect as well as illogical to maintain that they do. When you examine world religions, religions like Judaism or Hinduism or Buddhism, you will immediately recognize that they directly contradict one another. Moses taught that there was one God. Krishna believed in many gods. Buddha was agnostic. Logically they can all be wrong, but they cannot all be right. May I suggest you work out your own salvation with fear and trembling. “Thou believest that there is one God; thou doest well: the devils also believe, and tremble.” –James 2:19
