Passover rarely even falls at the same time because it's based on the 15th day of the Jewish calender month of Nissan.
Passover is the day that Christ was killed for our sins. It is the day that Christ specifically told his followers to remember his sacrifice on. Most of the Christian world has rejected Passover in favor of the the manmade tradition of Easter. Furthermore, the religious world mixes with the secular, which embraces idolatrous symbols, in celebrating Easter.
2Co 6:14 Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?
2Co 6:15 And what concord hath Christ with Belial? or what part hath he that believeth with an infidel?
2Co 6:16 And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people.
2Co 6:17 Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you.