My guess is that they are PC(USA), which is more a branch of the progressive movement than a body of Christ. Not judging the people, never judge the relationship Others have with Christ. Just judging the actions of the Denomination.
After some research, it seems that the BPC is actually more conservative than the PCA, so way more conservative than the PCUSA. In fact, it looks like some PCA churches are moving to the BPC out of concern over some PCA stances on issues, like women's roles in leadership.
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