Easter coincides with the vernal equinox. According to the New Testament, Jesus’ crucifixion and resurrection occurred about the same time as the Jewish Passover, which was celebrated on the first full moon after the vernal equinox. Both those who believe in the Good Friday to Easter Sunday and the Wednesday to Saturday timeline for Christ's death and resurrection do not argue this point. But, because of the differing phases of the moon, Christians celebrated Easter at different times and by the end of the second century, some churches celebrated on Passover and others celebrated the following Sunday.
Going to http://www.timeanddate.com/ can show any calendar from any year to see when Easter fell in any given year. But who sets the date for Easter and how do they decided? Why not celebrate on the day Christ was resurrected?
Well, for one thing, Christians, theologians, and scholars cannot agree on the day Christ was crucified or resurrected. Christians celebrate the Good Friday Crucifixion to Sunday morning resurrection timeline. But that's not three days and three nights. And according to Mathew 12:39-40, Christ was in the earth for three days and three nights.
Matthew 12: 39 But he answered them, "An evil and adulterous generation seeks for a sign, but no sign will be given to it except the sign of the prophet Jonah. 40For just as Jonah was three days and three nights in the belly of the great fish, so will the Son of Man be three days and three nights in the heart of the earth.
But according to some- http://www.herealittletherealittle.net/index.cfm?page_name=Jesus-Resurrection -Christ was crucified between 9:00 a.m and 3:00 p.m. He was then placed in the grave. Although this isn't a full 24 hours, it counts as the first day and first night in the grave. Thursday and Friday are days two and three and Christ arose on Saturday, the day then recognized as the Sabbath.
So, why don't Christians follow this time line? And why do we celebrate on different days and even months?
In 325 AD, the Council of Nicaea established Easter as the first Sunday after the first full moon and dependant upon the ececclesiastical approximation of March 21 for the vernal equinox. But if the full moon falls on Sunday, Easter is delayed one week, which decreases the chances of it falling on the same day as the Jewish Passover.
So, if Easter is celebrated at different times of the month, does it really matter whether Christ died on a Friday and was ressurrected on Sunday. Or if he died on Wednesday and was ressurected on Saturday? What matters is that Christ was tortured, ridiculed, and crucified for our sins. He was buried in a tomb where he lay dead for three days before his ressurection on the third day. And because he died, we migh live and have eternal life.Believing and having faith is what counts.