FTS, there is a reference to this somewhere in The Jesus Mysteries. More reference might be found in Art and Death in Imperial Rome and Christian Triumph, OUP, 1998. Also J Toynbee, Death and Burial in the Roman World, Ithaca, Cornell University press 1971. My favourite source for early Christianity is JM Roberstson, A Short History of Christianity. Watts and Co. second edition 1937. Robertson uses sociology to describe the religious habits of the worshippers and leaves us with a distinct impression of various pagan christ-cults competing for survival, totally at odds with the modern notion of divine attention given to one small group in the first century.
The early Jesus cult did adopt certain symbols such as the fish but then this was also found in the pagan christ cults (Pythagoreans and sacred geometry).The real cultural distinctions between pagan christs, notably Dionysus and Mithras and the Jesus cults were defined only after the Roman Church adopted the religion of Constantine in his thrust for unifying all religion. This took place in the first quarter of the fourth century followed by imperial edicts proscribing any other form of Christ to be worshipped and subsequently by careful destruction of evidence for the pagan origins of Roman Christianity; the one universal Catholic Church from which all protestant belief has later come. And I like to point out this includes JW beliefs.
Precisely what Roman 'religio' was in the second century would be useful to define.