Yesterday was Easter Sunday—or, as some people call it, Resurrection Sunday. While Easter is also a pagan holiday celebrating fertility and the rebirth that comes with spring, for Christians, Easter marks the date of Jesus' rising from the dead.

Throughout Christian history, the date of Easter has been hotly debated. Arguments that have caused problems for centuries include which sun to use as a base as well as which day the Bible says Easter happened on.

When what is now the United Kingdom was becoming an important location, the issue of date became harder to pin down. Eventually, Jerusalem's time zone was chosen as the official one, but that didn't end the debate as those in the United Kingdom and beyond couldn't always track that time. Some Christians were marked as heretics based on their schedule for Easter, and those who were accepted anyway still faced the disrespect of most of their peers.

Ultimately, of course, that part of the argument was solved by greater communication across distances. Some, however, persist to this day. Even with all of the disagreement, everyone agrees that it's important to celebrate – and it's important to celebrate in unity.

Other aspects of the holiday differ greatly within the Christian community as well. Some of these include how Good Friday is noted and the celebration of Lent. Every aspect is steeped in symbolism and ritual.

There are countless denominations of Christianity with countless approaches to religious ritual and celebrations. Even so, one thing that all of them can agree on is the importance of Easter. Of course, when you remember that Christianity is a religion is based solely in the death and resurrection of Jesus Christ, it makes sense why Christians would consider that a vital holiday.