A lot of people have this notion that welcoming (muslim) immigrants is like asking for terrorism, that they take away jobs, that they don't integrate well into society and they are out to convert everyone to Islam or something like that.
I don't know what makes believe these crazy ideas, but the media certainly doesn't help, painting every terrorist attack as something to do with immigration policy or muslims. Social media plays a major role in spreading all these wrong stories. Unfortunately the vast majority of internet users get their news from social media platforms, where emotional appeal of a story trumps facts, which is something fake news writers have exploited to great success.
I have no idea how people can support policies which actively want to stop helping immigrants. It's a humanitarian crisis and we need to do everything to help people who are suffering. As simple as that.