Some “mainline” Protestant churches have become apostate and have accepted sin in their ranks - see Episcopal, ELCA, PCA, United Methodist, et al.
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Please don’t include the PCA in your list of the apostate. The PCA is an “orthodox” Presbyterian denomination that broke away from the Presbyterian (U.S.A.) because the PCUSA was diverging from biblical beliefs and practices & has become apostate.
My apologies - I was referring to the PCUSA, of course.