Apparently he didn't get the memo that the fastest growing religion in the US is "no religion". This is also true for the 2nd generation of immigrants.
While American Muslims have higher retention rates, their kids are also becoming atheist (in the US) at a rapid pace.
In short, he's got nothing to worry about! What's going to happen? Easy: Religion will become a smaller and smaller factor over time no matter who we "let in" 😁👍
Jokes on him: Wolfenstein is more likely.