I’m trying to be very precise here in what the data provides and what the data does not provide. So we know that lack of evidence is not evidence of absence or absence of evidence is not evidence of absence. What that means is the fact that we don’t have evidence for widescale Torah observance before the second century before the Common Era does not necessarily mean that Judaism began then. It could be that Jews were keeping the laws of the Torah on a wide-scale basis in earlier periods in the third century, the fourth century before the Common Era. But the evidence simply hasn’t survived.For more on Professor Adler's work, see here and links.What I do in the final chapter is look at contextual evidence from the period before our terminus ante quem. So I’m looking at the evidence surrounding this question to see what was going on with Judeans in these earlier periods. And what I find is that what’s commonly thought of as the beginning of Judaism in the Persian period, in the fifth century before the Common Era, not only do we not find evidence of wide cultural observance, we find negative evidence.
I take his point about the problem with citing the Passover Papyrus from Elephantine as proof of the observation of Passover in the fifth century.
But that said, the biblical evidence for its observance is not inconsequential. The Deuteronomistic History has King Josiah reviving Passover observance (reportedly neglected since the days of the Judges) according to 2 Kings 23:22-23. If Dtr was written within living memory of Josiah, as many specialists think, that implies Passover observance was happening on a wide scale in Judah, presumably as an innovation, just before the Babylonian Exile. Of course one could argue for a later date for Dtr. But in any case it shows interest in the festival from long before the first-century CE evidence that Adler cites.
Also, according to the Chronicler, King Hezekiah revived Passover observance (2 Chronicles 30). And the Chronicler much expands the story of the Josianic revival of Passover (2 Chronicles 35). Some would date Chr1 as early as the fifth century. But even if we date Chronicles as late as the fourth or third century, the author seems to be disseminating pro-Passover propaganda much earlier than Adler's evidence. Does that imply "wide-scale" observance? Maybe. I don't know.
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