EARLY Christians...circa 70 c.e. to 300 c.e.? Those in 70 c.e. didn't have an official church, much less such rituals as Mass.
I wouldn't be too sure about either of those points. I don't have a Bible or my
Oxford Dictionary of the Christian Church with me here at work. However, clearly the ritual commemoration of Christ's last supper with his disciples had begun to take shape as early as Apostolic times; this is why some churches actually quote Paul, in I Corinthians, for the Words of Institution at Holy Communion, rather than quoting the Gospels. And I think I remember the
Oxford Dictionary of the Christian Church stating that the church at Rome had begun to celebrate the feast of Christ's nativity by the mid-200s, but my memory could be mistaken.