Islam doesn't "support" polygamy it allows it. If a man decides to marry more than one woman, he can. But if your'e going to marry many you must treat them equally and they must agree to marry you on...
I would say that "support to" is used to mean a literal support such as to hold up a roof. He added a steel brace to give more support to the roof. I would say "support for" to indicate approval for...