actually in the early Church the birth of Jesus was less important than Easter, the commemoration of his death and resurrection. Christmas and the associated events such as Epiphany and the Presentation became feasts much later, in large part due to the influence of Helen, mother of Constantine and later devout empresses. they made it their business to discover the actual locations of various events in the life of Jesus and Mary and to build churches on those sites. the early Church also usually celebrated a saint’s feast on the day of his death (usually by martyrdom), not his birthday, presumably because that would be the day he entered heaven.