I am a bit open-minded to the gay community about having access to such things as survivor benefits, insurance, etc.; but marriage is out of the question. The marriage ideal is A man, and A woman, in A committed monagamous relationship, for A lifetime!
Objectively speaking, polygamy is much less morally disordered than homosexual "marriage". (For example, the Mosaic Law permits polygamy, but punishes homosexual acts with death.) Society can't very well endorse a greater perversion while prohibiting a lesser one. The same goes for incest between consenting adults.
You probably meant the Muslim world, of which many are Arabs but certainly the minority.. There are probably millions of Arab Christians who consider polygamy to be as degrading as anyone. Polygamous marriage is a Muslim phenomenon...with many tribal societies adhering to it as well.