The point can't be made often enough: Germany's immigration policy is extreme and irresponsible.
Letting hundreds of thousands of able-bodied young males from the world's most violent and unstable areas into your country is extreme and irresponsible.
Not subjecting them to background or security checks is extreme and irresponsible.
Allowing thousands people with obviously fraudulent passports (g) to enter your country is extreme and irresponsible. Over 2200 people entered Germany with fraudulent passports. Although this is a crime with a sentence of up to 5 years in Germany and presumptively disqualifies you from claiming asylum, nothing was done.
And now for a look at a non-extreme policy. Here's an excerpt from the second US Presidential debate in which Hillary Clinton explains her proposal to permit 65,000 refugees from the Syrian civil war to relocate to the US:
Well, first of all I will not let anyone into our country that I think poses a risk to us. But there are a lot of refugees - women and children - think of that picture we also that four-year-old boy with the blood on his forehead because he'd been bombed by the Russian and Syrian air forces. There are children suffering in this catastrophic war, largely I believe, because of Russian aggression. And we need to do our part. We by no means are carrying anywhere near the load that Europe and others are.
But we will have vetting that is as tough as it needs to be from our professionals, our intelligence experts, and others.
The point is not whether you agree with this plan, or whether you think Clinton will do it right. The point is that this is the center-left position on refugee relocation -- women and children first, and strict security checks. A policy that balances humanitarian refuge with the legitimate interest in protecting domestic security.
The German government, by contrast, followed (and is still somewhat following) a kind of extreme left, open-borders, masochistic policy. It has intentionally refused to balance security with humanitarian imperatives, instead deciding to allow hundreds of thousands of random strangers into its country with no background checks at all, despite blatant evidence of fraud and concealment. The recent revelation that a 22-year-old Syrian male "refugee" was an ISIS operative who planned to bomb a German airport is only the latest evidence of how this policy has increased risks for ordinary Germans.
This is the necessary context to understanding why support for Merkel's party is dropping and the right-wing AfD party is increasing. Merkel, for reasons historians will speculate about forever, abandoned the sensible center-left consensus on this issue embodied by Clinton and instead chose an extreme-left policy which no other nation on earth thinks is responsible.