Should I force an Alignment Change on my party?

If the name Hasan means anything to you, kindly stop reading here, you know who you are.

Long story short, my party met with a woman in her village who recently had all the people in their temple mind controlled by an outsider. Both the letter she had given them and in dialogue with her was mentioned the hook I had come up with to make combat a little more interesting: Please don't kill anyone, as the people at the temple are our friends and family.

"-the young men and teachers of the village who study at the temple did not return to their homes. Their families worried and went to the temple, but were driven away by the students-" / "All of the villagers are in misery, for many of their sons are of the temple. Some have begged me to give myself over to the wicked man, but I dare not, lest I find that he has lied and will not break his curse on them." (from the letter), and in conversation with her when asked they said, "We'll try, but if it's us or them we're going to choose us." to which her response was "I understand."

My party went into said temple to find the man who had put a curse on the temple's acolytes. They, about 5 minutes in, decided "Non lethal is too much work" (not paraphrased) and slaughtered a dozen and a half of the temple acolytes.

When I asked about the decision making behind that after the session, the response I got from 3/4ths of them (one went to bed) was "Oh that's what you meant? I didn't know they were being forced/controlled into this"

I thought I was fairly clear.

Does this warrant Alignment changes, or is that too extreme? (2x are Neutral Good, 2x are Chaotic good)

Apologies for my atrocious formatting and rambling, If anyone needs more context I'll give it. Bonus points if you know what adventure I've been adapting.