Original sentence: Although The Oak Ridge Boys began releasing secular country songs in the late 1970s, but always maintained their gospel roots by recording religious material and performing gospel songs in their concerts
Edited sentence: Although The Oak Ridge Boys began releasing secular country songs in the late 1970s, always maintained their gospel roots by recording religious material and performing gospel songs in their concerts, and several of their songs during the peak of their mainstream popularity had Christ-like themes (even if God and Jesus were not speficially mentioned in the lyrics)