You are subscribing to the domino theory.  Applied to the Church it betrays a lack of faith.  The Church has many times "changed its mind" about doctrines and the rock-solid walls of its foundation have not collapsed.  To say that to admit one's errors is foolhardy is to prefer error over truth.  "Truth (that is, God) is unchanging but our understanding of it is not.  It is disastrous to confuse the two."