Even though that title probably grabbed your attention, and immediate bias, I promise that it wasn’t chosen just for “shock value”, but is the best general way to sum up my thought, and, by the end, whether you agree or not, you’ll understand why it’s the title.

Now, a necessary bit of background:
The Gospel of Mark is generally thought to be the earliest written of the gospels in the New Testament, with Matthew and Luke, and later John, coming after.  Mark, Matthew and Luke are known as the ‘synoptic gospels’ because they are so similar in style and content.  The consensus is that the authors of Matthew and Luke probably sat down with a copy of Mark and a copy of another gospel (usually labeled the “Q” gospel, from the German word for ‘source’: Quelle) and wrote their books from them.  So, if a story is in Mark, it’s one of the older stories (and closer to the actual lifetime of Jesus).  And if it’s also in Matthew and Luke, then I think it’s safe for us to assume that it was a generally widely accepted account of an episode from the life of Jesus.
The gospel story we’re concerned with here is the story of Jesus being asked whether taxes should be paid to the Roman emperor, or “Caesar”.
It is found in all three Synoptic gospels.  In Matthew, it is told in Chapter 22:15-22; in Mark, 12:13-17; in Luke, 20:20-26.  Also, though multiple gospels tell the same story between them, sometimes they don’t tell the same story.  Details are different, at odds, sometimes presenting irreconcilable differences.  Luckily, for us, this is not one of those times.  The story about Jesus being asked his thoughts on the payment of taxes is told, more or less, the same in all three gospels.
For our purposes, we’ll use the story as told in Luke:

Keeping a close watch on him, they sent spies, who pretended to be honest.  They hoped to catch Jesus in something he said so that they might hand him over to the power and authority of the governor.  So the spies questioned him: “Teacher, we know that you speak and teach what is right, and that you do not show partiality but teach the way of God in accordance with the truth.  Is it right for us to pay taxes to Caesar or not?”

He saw through their duplicity and said to them: “Show me a denarius.  Whose portrait and inscription are on it?”

“Caesar’s,” they replied.

He said to them, “Then give to Caesar what is Caesar’s, and to God what is God’s.”

They were unable to trap him in what he had said there in public.  And astonished by his answer, they became silent.

First, I would just like to point out the recognition–by Jesus–implicitly, at least, that there is a practical, real-world basis for the concept of separation of church (“God’s”) and state (“Caesar’s”–which, in the Roman Empire, the Emperor, besides being a god himself, was the state).  A recognition of the fact that some things were, and belonged to, the secular world, and that some things were, and belonged to, the sacred.  Second, that it was perfectly alright, and didn’t infringe upon your religious duties to separate them, and to serve your duties to each without it having to negate your duties to either.

Now, an observation.  With all the outroar and protests, especially recently in our history, I don’t think I have ever seen religious protests “defending marriage” at the Little White Wedding Chapel in Las Vegas, NV–even though this “quickie marriage” institution, as well as undermining the institution of marriage, statitistically produces more divorces on average than most other “chapels”.  And as a fundamentalist, evangelical friend of mine tried to argue the other day, according to Jesus, a divorced person is essentially always married to the first one and, though legally divorced, makes him/herself an adulterer for the rest of their lives, as well as making anyone who decides to be in a relationship with them an adulterer too.  Likewise, I don’t believe I’ve ever heard of a religious protest outside of a courthouse because of the fact that a Justice of the Peace is performing the role of marrying two people, and not a member of the clergy.  It seems that even those so quick to “defend the institution of marriage” recognizes that religion does not always have the sole responsibility over this institution, and they don’t really ever voice any concern that non-religious officiants are “moving marriage away from religion”.

So, that being said, I would like to put forward this idea (though I know there will be those who will subsequently tell me that I will, or should, burn in hell for it):

Even Jesus recognized, and supported, the idea that some things were for the state, and some for religion.  Taxes and money were a big thing back then, so it wasn’t something little that he was proposing.  Keep in mind that the whole reason they were asking him about whether it was okay to pay taxes to Caesar was to trap him in an answer that would allow them to bring him into custody and make him stand against charges.  So if the secular world says, “We are going to allow same-sex marriage,” and isn’t in the same acquiescence requiring priests and clergy to perform those marriages, that is an entirely “Caesar” kind of thing.

Even if you don’t support the idea, for religious reasons, that a man should be able to marry a man, or a woman a woman, the country and it’s government (which is very much, no matter how the Right may want to reinterpret, or fabricate, history and say that this country was founded as a religious, read: Christian, country) aren’t asking you to accept it religiously.  Those couples are perfectly happy being married by government officiants.  The “recognition” that these persecuted couples are so desperately happy to receive isn’t a religious one.  They are happy to be recognized LEGALLY.  Legal isn’t religious.  And it shouldn’t be.  (And it never was in this country.)

So in closing, I think I’ll go with the King James translation of one of those lines above (for which I used the NIV):

Render unto Caesar what is Caesar’s, and unto God what is God’s” — (just because it sounds a little more formal).