How to write devil in japanese

Francis Xavier 16th century Jesuit missionary once said that the Japanese language was created by the Devil to prevent the spread of Christianity in Japan. Undeterred by his perceived difficulty, he was widely known as the first person to introduce Christianity to the land of the rising sun. At first glance it seems that Japanese is unfathomable- the sentence structure is unfamiliar, it uses a multitude of writing scripts, and the readings for Kanji have not gone through a nationwide standardisation during that time. One of the difficulties of Japanese is there are just so many readings for a single character! When you look at a character dictionary, not only there are kun-readings native Japanese readings but there are also on-readings readings that supposedly sounds like the loan Chinese pronunciation. There are usually many on-readings for every single character!