Actually it is interesting that Catholic Poles are moving into the traditionally Protestant part of Germany. Bismark made sure to include enough Germanic Catholic regions to make his Germany large, but NOT enough to counterbalance the power center he created: the Prussian East.
20th Century German history would have been otherwise, had the formation of a true Germanic nation been otherwise . . .
As you say, the real battle is not between Christians, but Christians to keep Europe from Islamicization.
IOW, this is overall good.
The Poles I met did NOT have a huge distaste for Germans and Germany -- it was Russia they hated . . .