The position, in simple terms
The Catholic Church rejects the Santa Muerte cult. This isn't the isolated opinion of one priest or diocese: it's a consistent position, repeated by various official and semi-official Catholic voices in Mexico and other countries.
The Church's reasoning
The central argument is theological, not cultural: for Catholicism, only human beings can be "saints" — someone who lived the Christian virtues in communion with God. Death, by contrast, is described in Catholic doctrine as a consequence of original sin, not as an entity with its own will capable of granting favors. Catholic publications like Boletín Salesiano have been explicit: "death is not a person, it is a fact" — and therefore, calling her "saint" and worshipping her is considered, under that doctrine, an act of idolatry.
How strong is the rejection?
It varies by source. Some Catholic publications describe it simply as a "superstitious" devotion or one "foreign to the faith"; others, like the same Boletín Salesiano quoting Father Sergio Checchi, use stronger language, calling it "diabolical." Catholic.net, for its part, states that a practicing Catholic who venerates Santa Muerte commits what they call "a very grave sin," by attributing to her powers that, under that doctrine, don't exist.
What this doesn't mean
This is the institutional position — it doesn't describe the experience of the millions of devotees who do consider themselves Catholic and keep both practices at once, without feeling any contradiction. That tension between official doctrine and real popular practice is, in fact, the central theme of our guide on whether the devotion is a religion in its own right.
Related: Is it a sin to venerate her? · Is she a saint? · Who is Santa Muerte? · History and origin