It is not uncommon for enemies
and non-believers of
Catholicism to create an
argument against the succession
and therefore validity of
the Bishops of Rome as true successors
to Peter by proffering the history of the "bad
Popes." That
argument arises from a basic
misunderstanding of Sacred
Scripture.
The first response to be made
to the so-called argument from
the "bad Popes" is
admission that many men who held the
position of Bishop of Rome were not holy men.
Perhaps Peter
was the best model for human
failure in such a leadership role.
He denied Jesus three times
after being told he would do so.
Some (e.g., Peter, Judas) who
are called stumble and fall.
Some (Peter) repent and are
saved. Others (Judas) reject
that grace. It behooves us to
remember that Jesus does not
call saints, but sinners.