Simply, gays and lesbians would have more opportunity to flourish if same-sex civil marriage were legalized, and this added opportunity would not subtract from anyone else's.
The LDS Church's letter urging its members to support California's proposed marriage amendment uses the language of church doctrine ("ordained of God," "Creator's plan" and "sacred institution") that should not be the basis of civil or constitutional law that will be imposed on all. The letter alludes to non-religious concerns ("strengthening families" and "children are entitled to be born within this bond of marriage"), but same-sex marriage would neither weaken families nor cause more out-of-wedlock births.
Let's debate issues on their merits and not vote for doctrine just because it's doctrine.
South Salt Lake City