Liberalism, whether secular or religious, is a
sin. In the doctrinal order it is heresy, and consequently a mortal sin against
faith. In the practical order it is a sin against the commandments of God and of
the Church, for it virtually transgresses all the commandments. To be more
precise: in the doctrinal order, Liberalism strikes at the very foundations of
faith; it is heresy radical and universal, because within it are all heresies.
In the practical order it is a radical and universal violation of the divine
law, since it sanctions and authorizes all violations of that law.
Liberalism is a heresy in the doctrinal order,
because heresy is the formal and obstinate denial of all Christian dogmas in
general. It sets aside dogma and replaces it with opinion. Consequently it
denies every doctrine in particular. If we were to examine all the doctrines of
Christianity, which, within the range of liberalism, have been denied, we would
find every Christian dogma rejected in one way or another, from the dogma of the
Incarnation to that of Infallibility.