The first Christians, Jewish and Gentile, were certainly aware of the Hebrew calendar, but there is no direct evidence that they celebrated any specifically Christian annual festivals.Christians of Jewish origin were the first to celebrate the resurrection of Jesus. Since the date of the resurrection was close the timing of Passover, they likely celebrated the resurrection as a new facet of the Passover festival.Direct evidence for the Easter festival begins to appear in the mid-second century. Perhaps the earliest extant primary source referencing Easter is a mid-second-century Paschal homily attributed to Melito of Sardis, which characterizes the celebration as a well-established one.
Evidence for another kind of annual Christian festival, the commemoration of martyrs, begins to appear at about the same time as evidence for the celebration of Easter. But while martyrs’ days (usually the individual dates of martyrdom) were celebrated on fixed dates in the local solar calendar, the date of Easter was fixed by means of the local Jewish lunisolar calendar. This is consistent with the celebration of Easter having entered Christianity during its earliest, Jewish period, but does not leave the question free of doubt.
The ecclesiastical historian Socrates Scholasticus attributes the observance of Easter by the church to the perpetuation of its custom, “just as many other customs have been established,” stating that neither Jesus nor his Apostles enjoined the keeping of this or any other festival. Although he describes the details of the Easter celebration as deriving from local custom, he insists the feast itself is universally observed.