It is absolutely apropriate for a church to welcome all human beings into a church.
It is a tragedy that migrants are dying attempting to cross the desert. One good way to stop these deaths, is with a long fence... How about that for immigration reform. Stop illegal immigration cold, then raise and lower legal immigration levels as the economy needs. Mexico should become less corrupt and more condusive for investment, but that is mostly their problem to resolve.
A real question arises: Are not the migrants being exploited by the rich? Do they think that Mexico will ever have a just government when the ruling class of that country can export their needy to North America?