I think it spreads across all denominations.
Here’s a story on how the Catholic Church is contributing to the problem:
http://www.freerepublic.com/focus/f-news/2361228/posts
Apparently you have read our position statement, so you can see that we are not advocating a "pro-amnesty" position nor calling for "open borders." The NAE resolution called for an equitable process toward earned [emphasis added] legal status for currently undocumented immigrants, while urging the government to develop structures and mechanisms that safeguard and monitor national borders with efficiency and respect for human dignity.