We must now consider the vices contrary to peace, which belong to deeds: such are schism, strife, sedition, and war. In the first place, then, about schism, there are four points of inquiry:
(1) Whether schism is a special sin?
(2) Whether it is graver than unbelief?
(3) Of the power exercised by schismatics;
(4) Of the punishment inflicted on them.