To those who argue that marriage has always been betwen a man and a woman, let me respond:
Marriage has not always been between A man and A woman...different societies have had different norms. A man and a woman, a man and multiple women, a woman and multiple men (fewer, but they have existed), a man and a woman and a 2-spirited man (who would cross dress as a woman) who would be the husband's second wife (again, few, but it has existed), and there is even historical documentation of same-gender "friends" who have had their unions blessed by the church in the middle ages. Some cultures have allowed divorce and remarriage while others have not. Some have allowed young teens to marry (not appropriate for our day and time, but in the past it happened), and so on. Marriage has meant many things over many centuries across many cultures. Now, just b/c marriage has or has not looked a certain way in times past doesn't negate the need for us to what is just and fair NOW. And while many countries do not recognize gay marriage (yet), other countries do, some first nations do, and now some US states do. The trend will continue to move toward liberty and justice for ALL.