In History and Theology in the Fourth Gospel, Martyn argued that John 9.22 concerns the formal expulsion from the synagogue of Jews who were confessing Jesus as the Messiah of Jewish expectation. Johannine scholars following Martyn have often claimed that a ‘high’ Christology must have provided the catalyst for this trauma, not the ‘low’ Christology posited by Martyn. For Martyn, however, a ‘high’ Christology was a subsequent development, leading to a second trauma, that of execution for blasphemously claiming that Jesus was somehow equal to God. Accepting Martyn's argument on 9.22 with respect to this issue, and leaving aside the debate about the relevance of the Birkat ha-Minim, this article seeks to determine why local synagogue authorities, evidently represented in John's narrative by the Pharisees, would have found the acceptance of Jesus as Messiah so offensive that they formulated a decree to expel fellow Jews espousing this new messianic faith. Analysis of John 5, 7 and 9 demonstrates that the Pharisees in the Johannine setting found this confession offensive because they regarded the behaviour of Johannine disciples on the Sabbath as thoroughly inconsistent with their own understanding of the Sabbath commandment and as significantly hindering their desire to play an authoritative role in determining what counted as acceptable behaviour on the Sabbath and what did not. In short, the specific catalyst for expelling Jews confessing Jesus as Messiah from the synagogue was their Sabbath observance, which the Pharisees in the Johannine setting came to regard as an unacceptable deviation from their own developing views on the matter in the period after 70 ce.