In fact, the churches do respond more in communities with larger immigrant populations. Moreover, this response is not trivial. For each dollar reduction in government spending the church increased spending of 40 cents. This becomes an even bigger question if we start to wonder who is the more efficient provider of public services.
I will close with one final interesting but dampened note on this research. While the Welfare Reform Act had an impact on church spending it *did not* have an impact on donations. This seems to suggest that during this time churches were dipping into extra funds. In the short run this might be fine; however, if this were a sustainable form of charitable action donations would need to pick up in the long run.