As the Lord says, “Many are called, but few are chosen.” That the reprobate would be found within the Church was predicted by Him. Our holy faith preceded them and will last after they have been judged by it and gone to their reward.
As St. Gregory the Great commented on these words of the Lord, before there were any Episcopalians or Universalists, etc.
And it should not frighten you that in the Church the bad are many and the good few. For the Ark, which in the midst of the Flood was a figure of this Church, was wide below and narrow above, and at the summit measured but one cubit (Genesis vi, 16). And we are to believe that below were the four-footed animals and serpents, above the birds and men. It was wide where the beasts were, narrow where men lived: for the Holy Church is indeed wide in the number of those who are carnal minded, narrow in those who are spiritual. For where she suffers the morals and beastly ways of men, there she enlarges her bosom. But where she has the care of those whose lives are founded on spiritual things, these she leads to the higher place; but since they are few, this part is narrow. Wide indeed is the gate and broad is the way that leadeth to destruction; and many there are who go in thereat. How narrow is the gate that leadeth to life; and few there are that find it!