For what reasons does Karim think that the plan to go to Chlifa is impossible?

Karim says Maha's route goes straight through a Christian stronghold. He also tells her that even if she found a safe route for the eighty kilometers, the Syrians wouldn’t let a twelve-year-old girl and a baby through. Maha, in response to Karim's negativity, says she’d rather die with Jad than be separated from him in France, as Mrs. Farhat said they would be. When she sets off again, Karim hesitates but decides to join her. They can trade off carrying Jad. Karim realizes that to take this journey is the opposite of living in fear and hiding the way he has been.