John Piper outlines some thoughts on the homosexuality, marriage, and the law in response to the proposed Minnesota Marriage Amendment:

  1. There is no such thing as so-called “gay marriage.”
  2. Same-sex sexual relations are sin.
  3. Not all sins should be proscribed by human law, but some should be.
  4. The legal significance of marriage makes a statutory definition necessary.
  5. It is wise that our laws define marriage as between a man and a woman.

Read the whole thing for an explanation and defense of each point.

(For a compelling natural-law argument that “it is in the public interest for law and policy to take cognizance of [marriage] and support it,” I recommend this article by Robert P. George.)