All the people who don't believe what you do are infidels (unbelievers) from your perspective. To Christians, Muslims are the infidels.
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Christians and Jews call Muslims infidels. However, Muslims call Christians and Jews as "people of the book" as they are holders of the holy books Torah and The Bible that Muslims believe that these holy books are revelations of God.
Infidels Correction: Muslims called Christians Infidels. Christians called Muslims Saracens.
Christians and Muslims
Muslims consider anyone who does not believe in their way an "infidel". Infidel means unbeliever. The term was also used by Christians in the Crusades to refer to Muslims.
They called the non-Christians (mostly Muslims, but also Jews and other minorities) a number of things, mostly "infidels".
Heaven
To get to the other side?
During the Crusades, Christians and Muslims viewed each other as infidels because they practiced different religions. The term "infidel" was used to describe someone who did not adhere to one's own religious beliefs. This labeling helped dehumanize the enemy and justify the violence and aggression of the Crusades.
In that time, the Catholic church regarded most non-Catholics as infidels, but especially Jews and Muslims. The Crusades were fought by European Christians, many of whom were Catholics, with the goal of driving Muslims out of the Holy Land; many of the crusaders also directed their fury against Jews. I enclose a link about that time in history.
A Crusade is a call to arms to reclaim Jerusalem from the infidels(muslims). In the First Crusade the pope declared that if Christians should take up the cross then God will grant them access into Heaven. In other words (if you're not a Catholic or Muslim), a holy war.
Muslims call Alexander Iskandar.
Muslims call the temple of the Muslims Masjid, but in English u call it Mosque!
Muslims call their pillars/towers minarets.