The role of the peoples' opinion in teaching is to confirm their beliefs to those taught by the pillars of morality and wisdom who lead the One True Church.  Where the people find themselves not completely aligned with the Bishops, then they know they are in error and must change.  It's all very simple.  It's what Jesus taught.  Or if He didn't, it is what the Church taught, and it is infallible, as it teaches, so it must be obeyed, even when it is saying things Jesus never dreamed of.