A friend of mine — let’s call him “B.” — a musician and long-time Catholic who recently joined another church, got a letter from his pastor saying that he wouldn’t be able to perform at services in his old parish any more. The pastor had no problem with non-Catholics performing music at the parish, but for someone who left the Church to visit and perform liturgical music in our services would create “confusion” for the faithful.
The pastor was going a little bit lightly when he chose his words. The precise word, I think, is “scandal”: it means leading people into error or sin. He doesn’t want the faithful to think that the Church regards it with indifference when people leave the Church and join another body with different doctrines, a body with which we cannot share the sacraments, a body with its own system of authority apart from the Church’s unity.
B. posted the letter on the internet and many of his friends commented to sympathize and to grouse about how the priest could not possibly be a good man if he wrote such a letter.
I didn’t want to answer right there and get his friends all angry, but I did write him a private note.

Dear B.,
I imagine that getting the letter from Fr. K is a bit of a sting, and I’m sorry about that.
There is a real pain of separation involved when people move from one Christian communion to another. I’ve experienced it too, on coming from Evangelical groups into the Catholic Church years ago. For you, being barred from the choir loft at St. Helen’s is just one piece of that experience.
I hope you know how grateful I am for you and your musical service at the parish, and for all the good that you’re doing now.
Yet I also respect Fr. K for acting as a pastor. Perhaps he’s acting out of a sense of duty, trying in his way to call you back to unity, according to the Church’s faith. Or at least he doesn’t want the parish’s music ministry to contradict the Church’s striving for unity. To separate from one Christian communion and adhere to another is a serious matter: this is something on which Catholics, Anglicans, and Orthodox all agree.
Ecclesial communion is something that Vatican II wrote about: how we believe together, share the sacraments, and live under one authority in the Church. So Fr. K is acting on a long-established principle, not a narrow parochial point of view.
I don’t know if this makes it more comprehensible. But I’m running on, and telling you things you probably know already. God bless.
With sincere regards,
–RC