Those who don't believe in Jesus are going to suffer from their wrath. That's not even reward or the stick. Their whole families are doomed by being slayed by believers. I believe, it's called murder. 1 Samuel 15:3 Now go and attack the Amalekites ... - Bible Hub
Now go and smite Amalek, and destroy utterly all that they have, and spare them not, but slay both man and woman, infant and suckling, ox and sheep, camel and ass. English Revised Version Now go and smite Amalek, and utterly destroy all that they have, and spare them not; but slay both man and woman, infant and suckling, ox and sheep, camel and ass. https://www.patheos.com/blogs/dispatches/2015/01/22/yes-the-bible-does-say-to-kill-infidels/
What did Amalek do to Israel?
This role appears in several stories: In Exodus 17:8–16, Amalek makes war against Israel in the wilderness. According to 1 Samuel 30:1–2, the Amalekites invaded the Negev and Ziklag in the Judean/Philistine border area towards the end of the reign of King Saul , burning Ziklag and taking its citizens away into captivity.
Amalek - Wikipedia