[ArGee]

Abraham did not "try" to fulfill God's promises through Ishmael. He knew which lineage was the one of promise. That is why he took Isaac with him for the sacrifice and not the son of the bondwoman.

But this after Abraham had already tried to fulfill the promise through Hagar and G-d had told him that wasn't the right way and that G-d would provide a son.

I would agree with you on one point. While I do believe that marriage is only supposed to be between two, polygamy is a sin the way obesity is a sin, not the way homosexuaity is a sin.

Shalom.