The main issue at hand here is the Catholic seal of confession, which has an extremely long history in US law (and in the law in many other countries) as being protected under freedom of religion
We had a long history in law for the ownership of humans, and how humans can be treated by their owners...
Doesn't make it right, or even constitutional.
If my "strongly held religious beliefs" mean I must kill every fascist I see, am I protected by the first amendment? It's my exercise, and I must be able to exercise it, right?
Or, does the first amendment say the government cannot make laws that target religious folk, either for benefits or persecution?
Testifying that someone confessed to a crime is not hearsay. Hearsay is "Person X told me that Person Y did Z".
Testifying to someone confessing to you is exactly what cops do on the stand, when they testify about a confession a perp provided in an interrogation.