From the US Conference of Catholic Bishops;
"It is preposterous to claim that justice for immigrants isn't central to Catholic teaching. It comes directly from Jesus Himself in Matthew 25, 'For I was hungry and you gave me food…a stranger and you welcomed me.' Immigrants and refugees are precisely the strangers we must welcome. This isn't Catholic partisanship. The Bible is clear: welcoming immigrants is indispensable to our faith.
Caring for and about the 'Dreamers' is nothing more than trying to carry out that seemingly simple, but ultimately incredibly demanding, commandment. It is a commandment found throughout Sacred Scripture, reaching back to the Hebrew scriptures, including Leviticus, 'when an alien resides with you in your land, do not mistreat such a one' (Lv. 19:33). In fact, the Church has been pro-immigration since God called Abram to leave Ur: 'Go forth from your land, your relatives, and from your father's house to a land that I will show you' (Gn. 12:1). To suggest otherwise is absurd.
The witness of the Catholic bishops on issues from pro-life to pro-marriage to pro-health care to pro-immigration reforms is rooted in the Gospel of Jesus Christ rather than the convenient political trends of the day. We are called not to politics or partisanship, but to love our neighbor. Let's reject the forces of division that insist we make a false choice between our safety and our humanity. It is both possible and morally necessary to secure the border in a manner which provides security and a humane immigration policy.
Our pro-immigration stance is based on fidelity to God's word and honors the American dream. For anyone to suggest that it is out of sordid motives of statistics or financial gain is outrageous and insulting."http://www.usccb.org/news/2017/17-159.cfm