Complex sentence: The main purpose of the "Na gorakh Kavkaza" was to attempt to popularize the Jesus prayer, and it's considered the fundamental book of Imiaslavie and the center of all the controversy that surrounded that movement.
Split into simpler sentences: The main purpose of the "Na gorakh Kavkaza" was to attempt to popularize the Jesus prayer. It's considered the seminal work of Imiaslavie and the center of the controversy that surrounded that movement.