Is the date of Easter Christian?

"It appears clear from the earliest writings of the church fathers that the Resurrection was almost universally celebrated by the church...Polycarp understood from the Apostle John that the celebration was to be observed from the date of Nisan 14, while the tradition of the Western Church was to celebrate on the Sunday following the Passover."  

https://answersingenesis.org/holidays/easter/is-the-date-of-easter-of-pagan-origin/