There are errors everywhere in the world. Our children our not perfect. But we don't throw them away. If you look endlessly for perfection, you will be disappointed ...
Actually - Abraham had many wives (read your history). Sarah and Keturah were two of them. Hagar was not his wife, as Genesis clearly states that Hagar was his concubine (Genesis 16:1).
I agree -- God should not have to change His word. As I recall, Jesus is the "Word". Baha'is believe that each age requires new laws. I believe that we do not require new laws. What we need is more people living by the old ones. If we can't even adhere to the 10 commandments, what makes anyone...
I was raised as a Baha'i -- 3rd generation, in fact. But I didn't mesh with it ... or it with I. I am a Catholic now. And, as a scientist, I see too many holes in it. Where to begin?