The Tupelo, Miss.-based American Family Association on Monday dumped half a million dollars into the campaign for Proposition 8, the proposed state constitutional amendment which would ban same-sex marriage.

The donation — by far the biggest single contribution to the campaign to date, although the National Organization for Marriage, California has made 12 contributions totalling more than $921,000 — came on the same day that AFA founder Donald Wildmon was quoted as saying this will be a crucial, decisive battle:

The “culture wars” will be irrevocably lost, said Wildmon, if Proposition 8 (the “California Marriage Protection Act“ which states that “Only a marriage between a man and a woman is valid or recognized in California”) loses on November 4.

“If we lose California, if they defeat the marriage amendment, I’m afraid that the culture war is over and Christians have lost,” said Wildmon, “I’ve never said that publicly until now—but that’s just the reality of the fact.”

Wildmon pointed out that If the “homosexuals” were “able to defeat the marriage amendment defining marriage as between a man and a woman, then the culture war is over and we’ve lost—and gradually, secularism will replace Christianity as the foundation of our society.”

“California is a big dam, holding back the flood—and if you take down the dam in California, it’s going to flood 49 other states,” Wildmon maintained. “It will destroy marriage as it has been known for thousands of years, and with that the cultural decline that normally would follow.”

Even after the AFA’s donation, it looks to me as if the main campaign against Proposition 8 still has raised more money in big-ticket ($5,000 and up) donations so far — just over $3 million — than has the main campaign for it — just over $2.6 million.

And recent poll numbers don’t look good for Proposition 8, either. A Field Poll survey conducted July 8-14 found 51 percent of likely voters ready to vote against the proposed amendment, and 42 percent ready to vote for it. Starting out that far below the 50-percent-plus-one-vote mark needed for victory bodes poorly for any ballot measure.