Christ is risen!
The Coptic is "Kristos Aftonf" with the response "Khen omethmi aftonf," which is to say, "Christ is risen" and "In truth risen." The word "Pi" (pronounced pee) is sometimes placed before Kristos, which means "the."
Our beloved church of Alexandria inherited the Greek from what was then the dominant culture of the region. Thanks to the efforts of people such as Abba Shenouti the Archimandrite, what was native Egyptian culturally and linguistically was separated from the Hellenistic. Some things are best kept in their original form however, as several chants in the Coptic Orthodox Church remain in Greek.