No wonder people are coming up with conspiracy theories. Many of the "immigrants" are Muslims while the minorities that suffered from ISIS, the Yazidis and Christians, are mostly left behind.
Sunni Muslims are only around 60% of the population of Syria, and they are the backbone of the ISIS. Despite that, 99% of the Syrian refugees admitted to the United States and the European Union are Sunnis. It is almost impossible for Yazidis and Christians to get refugee status in these countries.
http://www.breitbart.com/big-government/2016/11/01/obama-administration-resettles-9935-refugees-u-s-first-month-fy-2017/http://www1.cbn.com/cbnnews/world/2017/february/what-new-report-that-99-of-syrian-refugees-are-muslim-means-in-debate-over-themThe Obama administration has resettled 13,210 Syrian refugees into the United States since the beginning of 2016 an increase of 675 percent over the same 10-month period in 2015. Of those, 13,100 (99.1 percent) are Muslims 12,966 Sunnis, 24 Shia, and 110 other Muslims and 77 (0.5 percent) are Christians. Another 24 (0.18 percent) are Yazidis.