That you can identify a practice that you believe goes beyond the bounds of validity does not forclose the possibility of variation. For example, most Christians believe that members of other religions are not necessarily condemned to hell for lack of Christian conversion.
Gee,if you're saying what I think you're saying, I think that goes without saying.
But once a church has varied itself so far away from anything Scriptural as to be actively contradicting it, it's not really Christian anymore, and its poll numbers among "most Christians" aren't the determining factor of its validity.
For example, most Christians believe that members of other religions are not necessarily condemned to hell for lack of Christian conversion.
Absent faith in Jesus, or a covenant with God, it is a pretty poor lookout. There remain justification by works (virtually impossible for most, which is why Jesus died for us) and outright mercy (not impossible).