5.6. Can the Catholic Church give invalid sacraments? Isn’t that impossible?
The true Church cannot give invalid sacraments — this would violate Christ’s promises and the Church’s indefectibility. However, the modern post-Vatican II institution is not the true Catholic Church, but a counterfeit church that has arisen in its place.
As Pope Leo XIII taught in Apostolicae Curae (1896), a sacrament is invalid if:
It uses the wrong form or matter,
It fails to signify the reality of the sacrament,
The minister lacks proper intention or valid orders.
These conditions apply to many Novus Ordo sacraments. If the form has been altered in substance, or the minister is not validly ordained, or the intention is corrupted (e.g. seeing the Eucharist as a symbolic meal), then the sacrament is invalid, and no grace is given.
Therefore:
Faithful Catholics must avoid doubtful sacraments.
One cannot fulfill the Sunday obligation at a doubtful or invalid Mass.
Receiving a doubtful sacrament can be objectively sacrilegious.
This is why traditional Catholics insist on sacraments administered by validly ordained clergy, using the pre-Vatican II rites.