Early Christian tradition puts the date of Jesus rising from the dead on this day, making it the first Easter. April 23 would not be the day of Easter again until the year 2000.
The literal, physical resurrection of Jesus will become the defining feature of Christian theology and practice. There is some question, though, about whether all of the earliest Christians believe that Jesus physically rose from the dead, or if instead his soul was taken up into heaven and given a new body.
The former will become the dominant view, but this is due at least as much to politics and human decisions as it is to anything else.