charity, so too schism and heresy are different vices, although
whoever is a heretic is also a schismatic, but not conversely. This
is what Jerome says in his commentary on the Epistle to the Galatians
[*In Ep. ad Tit. iii, 10]: "I consider the difference between schism
and heresy to be that heresy holds false doctrine while schism severs
a man from the Church." Nevertheless, just as the loss of charity is
the road to the loss of faith, according to 1 Tim. 1:6: "From which
things," i.e. charity and the like, "some going astray, are turned
aside into vain babbling," so too, schism is the road to heresy.
Wherefore Jerome adds (In Ep. ad Tit. iii, 10) that "at the outset it
is possible, in a certain respect, to find a difference between
schism and heresy: yet there is no schism that does not devise some
heresy for itself, that it may appear to have had a reason for
separating from the Church."
_______________________

SECOND ARTICLE [II-II, Q. 39, Art. 2]

Whether Schism Is a Graver Sin Than Unbelief?

Objection 1: It would seem that schism is a graver sin than unbelief.
For the graver sin meets with a graver punishment, according to Deut.
25:2: "According to the measure of the sin shall the measure also of
the stripes be." Now we find the sin of schism punished more severely
than even the sin of unbelief or idolatry: for we read (Ex. 32:28)
that some were slain by the swords of their fellow men on account of
idolatry: whereas of the sin of schism we read (Num. 16:30): "If the
Lord do a new thing, and the earth opening her mouth swallow them
down, and all things that belong to them, and they go down alive into
hell, you shall know that they have blasphemed the Lord God."
Moreover the ten tribes who were guilty of schism in revolting from
the rule of David were most severely punished (4 Kings 17). Therefore
the sin of schism is graver than the sin of unbelief.

Obj. 2: Further, "The good of the multitude is greater and more
godlike than the good of the individual," as the Philosopher states
(Ethic. i, 2). Now schism is opposed to the good of the multitude,
namely, ecclesiastical unity, whereas unbelief is contrary to the
particular good of one man, namely the faith of an individual.
Therefore it seems that schism is a graver sin than unbelief.

Obj. 3: Further, a greater good is opposed to a greater evil,
according to the Philosopher (Ethic. viii, 10). Now schism is opposed
to charity, which is a greater virtue than