What is law, but an expression of the values of the society? If gay behavior is no longer perceived as sinful (wrong), the law would simply reflect that. The battle is with the culture and values. Using the courts and the law is just a means to the end of changing the culture, and the activists are generally more effective in using the legal system. But they want to change the culture, and to do that, you need to collapse the pillars of resistance. They effectively neutered most churches, the military, and have captured popular culture. The institution of marriage is a popular target that is inexorably yielding so, as funny as it may seem, the NFL actually represents one of the last strongholds against acceptance and celebration. Eventually it will give way too.