Mark Shea talks about it in this excellent post, not about normal Catholic devotion to the Blessed Virgin, but about Protestant terror of it. This has set my mind to ordering a few copies of his book, "Behold Your Mother: An Evangelical Discovers the Blessed Virgin Mary". In this post, Mark makes an excellent point about how extremes in denying the biblical blessedness of Mary lead to unscriptural and incorrect beliefs about the Incarnation and the Gospel. Such errors persist, however, and result in oddities such as the picture of our Lord as an inhuman savior who never called his mother "Mother", or that of a disconnected redeemer who, not having partaken of the human material of his "mother", did not really redeem the children of Adam and Eve after all.
Of course, I would, as a good Catholic, condemn the errors of Mariolatry, and I have seen signs of it, growing up in the Philippines. Now Filipino Catholics have not started offering a sacrifice (which is what worship is in the Judeo-Christian context) to Mary (or of Mary). Feasts of saints, including Mary, are still celebrated within the proper context of the Eucharistic celebration (Mass), where we unite ourselves to the one redemptive sacrifice of Christ in Calvary, offered to the Father. However, in a few places (such as Quiapo and Tondo), frequent and popular Marian novenas, as well as the occasional processions, seemed excessive. I wouldn't know personally if people actually prefer to pray novenas rather than go to Mass. Perhaps I see a lot of novenas being prayerd because they are simply unable to reconcile weekday Mass times with their busy schedules. I did not see excesses in my hometown of Lucena, even coming from the Holy Rosary Catholic School, even where Marian devotion is naturally encouraged and thriving. We had a rosary rally in October, celebrated in some years. I remember them as prayerful celebrations, meditating upon the mysteries of the rosary. We have Flores de Mayo once a year, although I seem to remember that more as a beauty pageant, much as our Queen Rose of Mary fund-raising pageant in school.
I am sure that there are abuses in Marian devotion. I do not see this as a general indictment, therefore, of Marian devotion, for I remain a Marian devotee, as was my primary and high school, as well as the university where I attended college -- and I did not see the excesses there. After all, who would say that sinners among us indicts Christianity or the Body of the Christ in general? Of course, I do understand the frustration of some, who attended in a Catholic school and came away with a different experience. The Lord warned about false teachers vividly, but the Lord also promised the Spirit of Truth, as well as a charism of certitude based on the keys of the kingdom to St. Peter in particular, and delegated authority to the apostles in general.
My Lutheran friend is incredibly frustrated at this, but his conclusion is correct: the Magisterium is indeed the official teaching authority of the Church. I cannot put in any differently, but his ire towards the notion of improper catechism in Catholic schools is not misguided. Well-meaning and reasonably catechized teachers can and do commit mistakes, if not deliberate abuses. In college, my RE teacher was caught up in liberation theology. Some of it was right, some of it was wrong, and it was the Magisterium which clarified that for me. In high school, our priest gave me some bad advice which I corrected only after clarification with the catechism and another priest.
My Lutheran friend is correct in indicting that the Church has a responsibility to address devotional abuses in our country. It is almost certain that they can do a better job of it, but I have no certainty that they haven't been doing their best. I did not personally encounter such Marian excesses in my life as a Filipino Catholic, and there are certainly none here in Melbourne. Perhaps the schools and parishes I've joined have simply been blessed like that and his were sadly not? But to say that the Church numbers among her members saints and sinners, orthodox teachers and heterodox ones -- what makes this so improbable?