Are you suggesting that our country's immigration policy is illegal? That anyone should be permitted to waltz in and be treated as a citizen? The "we Catholics" you mention had better realize that not all Catholics agree with them and with bishops who advocate breaking our laws. And I'm not referring to "outsiders" here.
That Bishop Lynch was on the list of bishops came as no surprise to me. This man did nothing to save the life of Terri Schiavo who was starved to death in Florida. His opinion matters not one iota to me.
No body, especially the Church, is advocating the breaking of laws. It is only calling on reform of a broken system in a way in which the rights of the immigrants are recognized.
As Christians, we can't claim to love God and then ignore the needs of our neighbors. Loving God is like loving a spouse. A husband may tell his wife that he loves her but to fulfill his obligations and demonstrate his love she will need to see the proof in his actions. Likewise if we claim to be "Catholic," we need to prove it by our behavior and serving other people by working for justice, charity and truth in our nation's political life is one of the very important ways we do that.
The "separation of Church and state" does not require that we as private citizens separate our Catholic faith from our public witness, our political choices and our political actions. That kind of separation would require Christians to deny who we are; to repudiate Jesus when he commands us to be "leaven in the world" and to "make disciples of all nations." Our founding fathers depended on a religious people for our experiment to work and the manifest faith and the convictions of Christians of all denominations have for the most part kept the promise that our Declaration if Independence trumpeted.
If you would you rather have a Church that did not choose the path of conscience and compassion you could always become a Calvinist. Just don't expect a lot of company.