The Catechism is not infallible.
My position is sufficiently explained in my post above. It is based on the teaching of the Church as to what constitutes a mortal sin. It is based on the teaching of the Church on positive precepts, which are not continuously binding (See VS on that point).
The above-stated objections of several posters ignore my theological arguments completely, and make no theological arguments of their own. Merely citing the Catechism is not a theological argument.
Regarding the example of the the nuns who missed Mass for lengthly periods of time to minister to aboriginals. The Bishop who condemned this practice and who ordered the nuns to be certain to either have a priest with them, or not to go out to the aboriginals to minister to them if they would miss Mass, changed his position and admitted that he was wrong. The nuns ignored his original order, since they were following the Gospel, which supercedes particular temporal decisions of even the local Ordinary.
So, if anyone follows whatever the Catechism says, ignoring Tradition, Scripture and other documents of the Magisterium, then such a person is not living the Catholic faith, but some new kind of religion based solely on the Catechism. Now I know from other discussions that some of the above posters do not take the Catechism to such an extreme, but there are some Catholics in the Church whose faith is based more on the Catechism than on Tradition, Scripture and other documents of the Magisterium.
But if you still think that I am mistaken, can you make a theological argument based on Tradition, Scripture and other documents of the Magisterium, without reference to the Catechism? Or if an idea is only found in the Catechism, and not elsewhere, is it a teaching of the Church?