Roman Catholic Archbishop Salvatore Cordileone of San Francisco has decried passage of a gay marriage law in Rhode Island.

On Thursday, hundreds of jubilant supporters joined independent Governor Lincoln Chafee as he signed the bill into law, making Rhode Island the 10th state to legalize gay nuptials.

(Related: Gay groups cheer Rhode Island gay marriage; And a video, too.)

In a statement issued the following day, Cordileone described the law, which takes effect August 1, as “a serious injustice.”

“The meaning of marriage cannot be redefined, because its meaning lies in our very nature,” said Cordileone in a blog post at the United States Conference of Catholic Bishops' (USCCB) Marriage Unique for a Reason website. “Therefore, regardless of what law is enacted, marriage remains the union of one man and one woman – by the very design of nature, it cannot be otherwise.”

Cordileone, who heads the USCCB's Subcommittee for the Promotion and Defense of Marriage, added that such unions hurt children.

“Marriage is the only institution that unites a man and a woman to each other and to any child conceived of their union. While those making great sacrifices to raise their children in less than ideal circumstances need and deserve our love and support, we cannot claim to have a just society if we do not look out for the most vulnerable among us: children. That means preserving in the law the principle that every child deserves a mother and father united in marriage. That means supporting in our institutions and in our culture the true and unique meaning of marriage,” Cordileone said.

Earlier, Rhode Island Bishop Thomas Tobin warned Catholics against attending gay weddings.