Largest religious organization that supports same sex marriage?

So, the United Church of Christ has voted to endorse same sex marriage, making it the largest Christian denomination to do so, according to the linked article.

So, what’s the largest non-Christian denomination to support gay marriage? It can’t possibly still be Reform Judaism, can it? I know that was the case when RJ voted to endorse it, but that was five years ago.

Also, is this only in the US, or worldwide?

The only other non-Christian church that I know of which accepts same-sex marriage is Unitarian Universalism, and the figures I’ve found seem to indicate that Reform Judaism is significantly larger than UUism (roughly 3.75 million vs. roughly 800 thousand worldwide, respectively.)

From what I understand, only the American Unitarians are also Universalists.

There is a Unitarian Church in Dublin, but it has broadly a Christian service. However belief in the divinity of Jesus, his resurrection and the Virign Birth are voluntary.

It is cerainly not the same as a UU church, even if the have similar beliefs about social policy.