Eyal Ben-Ari tugged at the heavy assault rifle hanging over his shoulder as he tiptoed out of his pink house at sunrise, hoping not to wake his wife or six children.

Walking to synagogue in Safed, a hill town above the Sea of Galilee known for centuries as a center of kabbalah, or ancient Jewish mysticism, he said he still didn’t feel great about the gun.

Sleeping with the rifle under his pillow, he worried about it being stolen. After his 13-year-old son came home with a toy replica, Mr. Ben-Ari considered returning the real thing, doubting his decision to join the newly formed civilian militia that had given him the weapon.

“I feel like it’s very — artificial,” he said, struggling to find the right word in English, looking down at the gun. “It’s not human. It’s not life.”

At the synagogue, men with graying beards and black suits — all fellow members of the Chabad movement, an ultra-Orthodox sect of Judaism — slapped Mr. Ben-Ari on the back. They were happy to see him. Happy to see his gun. It was the only one there, but far from unique. In this small city near the Lebanon border, where Hezbollah’s rockets have often rained down in recent months, Israel’s deep sense of vulnerability has led to a surge of citizens arming themselves.