Same Sex Marriage in the Image of God?

Yesterday I was asked to participate in a Chapel Conversation on campus. This particular Chapel Conversation is called "Jesus is Crackers" and it takes on controversial topics. The speaker is to address a hot-button topic by presenting both sides of the issue.

There are two microphones, one on each side of the stage. You are to start on one side of the stage and argue one side of the case. You then walk to the other microphone and disagree with yourself. And then the chapel ends on that open-ended note.

My assigned topic was same sex marriage. Specifically, can same sex marriages be considered holy and sanctified? Phrased another way, are same sex marriages reflections of the image of God?

This was my argument for the position that, no, same sex marriages are not reflective of the image of God:

Same sex marriages are not in the image of God because when God created humanity in God's image Genesis 1.27 says "male and female he created them." Thus, the model for marriage is Adam and Eve. The basis of marriage is biological complementarity. This understanding is supported in Romans 1 where Paul describes same sex relations as "unnatural." In light of this, the command God gives to marriage, as a reflection of God's image, is reproduction ("be fruitful and multiply"). Obviously, same sex marriages are not based on biological complementarity and cannot procreate. Thus, same sex marriages cannot reflect the image of God. The theology informing this understanding is creation theology.

This was my argument for the position that, yes, same sex marriages are reflective of the image of God:

Same sex marriages are in the image of God because the model for marriage is Yahweh and Israel rather than Adam and Eve. Thus, the basis of marriage is grace and election, God choosing Israel from among the nations. The primacy of election/grace over biology is supported in Romans 11 where God is found "unnaturally" grafting the Gentiles into the covenant with Israel. In light of this, the command God gives to marriage to reflect God's image is covenant faithfulness. Obviously, same sex marriages display the grace of election and can model covenant faithfulness. Thus, same sex marriages can reflect the image of God. The theology informing this understanding is salvation history.