Jerusalem was the goal of the Crusades, the Popes promised instant entrance to heaven for any crusader killed, & the popes, God's (Christ's) representatives on Earth, sanctioned the Crusades, giving indulgences to kill muslims. That's what the picture implies, & it is accurate, if, somewhat one-sided. But “I want you” posters are inherently one-sided. WWII recruitment posters were no less brutal or direct.
Regardless of which side you favor, those are the facts. Whether the Crusades were Right or Wrong doesn't change those facts.
You need to remove those ideological glasses sometimes. Maybe you will see more clearly & not be so ugly to reasonable people.
If you have a complaint, take it up with the teacher.
I'm sorry, but that is rot. There were no indulgences to kill Muslims.