I've reduced my offerings greatly to the Presbyterian church as the "rulers" are so far in left field that I don't want to support their values! I remain at my church right now for the fellowship with wonderful Christians who are also very upset with their rulings. Once they open to homosexuals, I'm out of there.
Ask your pastor or elders if the local church withholds its 'per capita'. If the answer is yes, you can probably safely continue to give at your old levels. If the answer is no, you shouldn't give them a cent, tell them why, and give directly to Christian missions and missionaries.