When the regime’s henchmen execute his entire congregation, a grieving priest infiltrates the tyrant’s palace as the new concierge, determined to detonate a bomb on the balcony of the Great Belfry as the tyrant addresses the crowd.

When soldiers massacre his congregation during midnight mass, a priest and former bomb disposal expert abandons his collar, infiltrates the dictator's palace posing as an organ tuner, and wires the instrument to kill him mid-speech.

Here is my version, distilled to what I suggest is its essence:

After a dictator's henchmen executes his entire congregation, a priest takes revenge into his own hands by infiltrating the regime's staff in order to assassinate the dictator.

That comes to 27 words versus the 32 words in your original version. It distills the logline down to the basic recipe: inciting incident + protagonist + antagonist + objective goal.

In addition, it focuses on the USP, the unique selling point, of your logline. Which I suggest is the *man* more than the modus operandi. The protagonist is a priest who is violating his vows, intentionally breaking all the Biblical injunctions against murder and seeking revenge.

Being obsessive-compulsive about logline word length, my first impulse was to distill it further to 20 words: "After a dictator's henchmen executes his entire congregation, a priest infiltrates the regime's staff in order to assassinate the dictator."

But I decide to add 5 more words to elaborate the dramatic moral conflict .

Either version raises interesting questions:

How does he justify his actions to himself -- and to others? And how does he go about worming his way into the regime? (It can't be easy.)

I, for one, would be interested in a movie that provides credible answers and a satisfactory cathartic experience.