The 2 most Baptist ridings are West Nova (22%) and Tobique-Mactaquac (19%). In both of these ridings Baptists outnumbered Anglicans, United Church and Presbyterians combined.
Next is Fundy Royal (18%), Kings-Hants (17%), and New Brunswick Southwest (16%).
The difference is larger if you consider other Evangelical groups. Pentecostals have a significantly larger market share in rural Anglo New Brunswick as do "Other Christian". Now "Other Christian" includes a lots of non-Evangelical stuff like Mormon, JW, Dutch Reformed etc, but its a pretty good proxy for generic evangelicalism.
However, I see your point. The difference in Evangelicals is nowhere near enough to account for the difference and in Nova Scotia, the most conservative ridings are mostly mainlines!
With that in mind I suggest the linguistic divide is the deciding factor.