What ruined Germany, and led to the mass influx of Muslims, was the reunification of the country. The former East Germany was far more effectively Communized than, say, Poland or Hungary. Formerly a mostly Lutheran region, 40 years of atheistic propaganda converted a majority of East Germans to becoming irreligious. In addition, they became used to cradle to grave welfare and programmed to slavish obedience to authority. Angela Merkel was a member of a Communist youth group and may have worked with the Stasi, the East German secret police.
Merkel is Stalin's ultimate revenge on Germany.