(from the Globe and Mail)

One of the great contributions of Christianity to the evolution of marriage was to extend it to groups which had been excluded. Gradually, poor people were allowed to marry. Then, against the will of lords and masters, the church extended the freedom to marry to slaves. Finally, some Christian denominations extended marriage to their clergy. Through this elastic process, the institution of marriage embraced more and more people. Now, people of different races and different religions are able to marry. Extending marriage to people of the same sex may be the final frontier and the logical conclusion of this evolution.