If you are a lawful permanent resident in possession of your green card and a valid passport and are otherwise admissible to the U.S. you should have no problem returning.
The question your really need to know the answer to is whether you require a visa to enter the Bahamas. The answer to this question has nothing to do with your U.S. immigration status. Rather it has to do with your country of citizenship and whether the Bahamas requires citizens of your country to obtain an appropriate visa in advance. You can get this informaton from a Bahamian Embassy or Consulate in the United States and application proceedures if a visa is required.
If a visa is required and you do not have one in your passport the cruise line will refuse to board you (they can be fined for bringing you to a country without proper entry documents far in excess of your cruise fare) so you should address this issue immediately as time may be of the essense. Enjoy your cruise!