On an individual basis, i.e. you don’t hit the entire denomination, but you MUST punish renegade priests and ministers and rabbis who use their premises to house these people. And the congregants in those churches should in some way be made to pay for these actions, as well as the clergymen responsible.
Its the only way to stop this nonesense.
The world is full of people who are needy. Obviously we can’t accept them all and equally obviously thier governments should be responsible for dealing with these issues, not the American taxpayers.
What kind of punishment would you suggest for those priests? Putting them in jail for helping the homeless and/or the needy?
Churches will tell you, and quite rightly, that Jesus said to help the needy without regard to status, legal or otherwise. Getting the government to interfere with that (and in a very religious country as we are) is inviting big trouble from the masses. When it comes to choosing between a mandate from God to help the needy and a mandate from the government to stop, the churches will tell the Feds to go to hell.
Your solution is impossible in a practical sense.
People on this thread are putting too much blame on the Mexicans. The problem is with Joe and Jane America, who are doing all the hiring. That's where your anger needs to be directed, folks.