The only thing I saw that even made partial sense is Merkel knows German population is in decline and she wants to see Germany retain economic and size supremacy in Europe. She believes she can make these immigrants' next generation into Germans.
It sounds stupid, I know. Maybe Merkel simply is stupid. Otherwise one starts to get into all kinds of conspiracy theories which lack strong evidence at this point.
Secularists like Obama simply cannot comprehend religious motivation. In their ideology, religious motivation is simply a cover for economic motivation.
Their ideology requires the dismissal of religious motivation, and that's the best explanation they've got.