Is this the real issue behind gay marriage...?

I think the real issue behind 'gay marriage' is that..
If the courts say same sex marriage is legal at the Supreme Court level, will a priest/pastor be forced by the state to marry a homosexual couple..?
In my opinion, one of the biggest issues with same sex civil unions, is the complications that it will produce in the potentially looming mixture between church and state.
Today the homosexual community is discriminated against because same sex unions are not recognized the same way as traditional marriage. The issues of insurance, adoption, racism, are all defining points, and matter with grave importance to those who these issues effect, aswell as whom oppose them. These points are for the most part social issues, and should be delt with in the proper place.
I think the major problem the courts understand that they are unprepared to deal with, is the fact that if the Supreme Court legalizes gay marriage, all of the preist/pastors could be found guilty of discrimination for not marrying a same sex couple. How would the Federal government define it's role in this? With the Civil rights movment, the Fed had to get directly involved in the changes that the movement produced, schools, buses, voting rights, employment and wages, ect... Would the Federal government step into the church, and pass legislation saying it was illegal to refuse marriage to a same sex couple..?
This seems to be the obvious collision that the church and state are on..
How would the state justify rewriting church 'beliefs'? How could the church deny Federal law? I personally belive that in a land of civil freedom, it is discrimination when one group of people are at a disadvantage to another because of a cultual, or personal beiefs.. or orientation... This is only one point in a very complex issue, and I hold personal belief that our constitution was written exactly for these challenges..