This may come as a shock to a certain blog-happy priest.
In his 1947 Encyclical on the Sacred Liturgy, Mediator Dei, Pope Pius XII attempted to set the record straight – and prophetically so, as we shall see – concerning the true relationship between the sacred liturgy and sound doctrine. He described the issue immediately at hand as follows:
…the fallacious reasoning of those who have claimed … that the Church is obliged to declare such a doctrine sound when it is found to have produced fruits of piety and sanctity through the sacred rites of the liturgy, and to reject it otherwise. Hence the epigram, “Lex orandi, lex credendi” – the law for prayer is the law for faith. (Mediator Dei 46)
“But this,” he tells us, “is not what the Church teaches and enjoins.” (ibid., no. 47) Getting to the heart of the matter, the Holy Father writes:
But if one desires to differentiate and describe the relationship between faith and the sacred liturgy in absolute and general terms, it is perfectly correct to say, “Lex credendi legem statuat supplicandi” – let the rule of belief determine the rule of prayer....
NB: The entire liturgy of the one true Church of Christ – every aspect and portion of it – is comprised of, and gives witness to, the Catholic faith. This means that unsound doctrine has no place whatsoever in the liturgy of the Church; it is not enough that it be primarily, mostly, or even overwhelmingly comprised of the true faith.