Non-Christian Weddings? What do you think?

As a Christian pastor I will gladly perform a wedding ceremony for a Christian couple. I will, under no consideration, perform a wedding for an unequally yoked couple (1 Christian and 1 non-Christian). But, until this last week, I've never been faced with the prospect of performing a wedding for a non-Christian couple and I'd love to hear your thoughts as I think this one through.This last week I've received two requests to perform a wedding for non-Christians.I've never been faced with such requests before and so I'm thinking through the theology of all this for the first time. On the one hand, I want to say "no" to both requests because I believe that marriage is designed to have Christ at the center of it. Marriage is, as the apostle Paul makes clear, a reflection of the union we have with Christ. Without Christ, a marriage may (in the best of circumstances) be pleasant and manageable, but it won't be deeply healthy and it won't center on Christ. So, on this line of thinking I'm inclined to say "no," not wanting to be responsible for joining a couple into a marital union that doesn't center on Christ and that has a lesser chance of survival.On the other hand, these two couples will get married no matter what--whether I'm the one who performs the ceremony or not. Plus, the gospel calls me to love my non-Christian neighbors and to find points of common grace where I can affirm my neighbors' hopes and aspirations, showing them that these hopes will find their true resolution only in Christ. Along this line of thinking, there's a case to be made that I could perform a non-Christian wedding in such a manner that's faithful to the gospel and loving to the non-Christian couple. To do so I would need to make it clear and compelling to these couples that their marriages can become truly great and healthy only through grasping the unbreakable marriage we have with Christ--the ultimate groom who suffered in order to cleanse filthy sinners, clothe us in spotless white robes, and bring us into eternal union (marriage) with him. This line of thinking makes me want to say "yes" to the wedding requests.Perhaps I could have a significant ministry to these couples (through some pre-marital counseling sessions and through the ceremony itself) and to the family, friends, and prison guards in attendance at the ceremony?What do you think? Please take a moment to share your comments and thoughts. I'd really like to hear what all of you think about this.