John 2:13, Passover of the Jews. (See also John 5:5; 6:4; 11:55; 12:1; 13:1.) Have you ever wondered why John often uses this phrase? What other Passovers were there that necessitated specifying which Passover he was referring to?
This “Passover of the Jews” is in opposition to the Passover feasts held by competing religious sects of the time (e.g., the Essenes at Qumran and the Samaritans). The modern Samaritans following ancient calendric traditions, for example, will hold their Passover on May 4 in 2012 as opposed to April 6, which is this year’s likely date on the biblical calendar.
The ancient Qumran community embraced an “unorthodox liturgical calendar that [set] them apart from the rest of Jewry” (The Complete Dead Sea Scrolls in English, by Geza Vermes, p. 41). For example, on the Qumran community’s solar-based calendar that is based on a 364-day year, the Passover always fell on a Wednesday (Ibid. p. 79).
As you can see, determining on what days the biblical feasts fall was as controversial then as it is now!
(For additional enlightening studies on the biblical calendar, check out my articles at http://www.hoshanarabbah.org/pdfs/cal_demyst.pdf and http://www.hoshanarabbah.org/pdfs/new_moons.pdf and http://www.hoshanarabbah.org/pdfs/vis_moon.pdf.)