KIRYAT ARBA, West Bank—Military towers loom over the highway leading to far-right lawmaker Itamar Ben-Gvir ’s hometown, a settlement next to the Palestinian city of Hebron. Residents walk around with pistols strapped to their thighs, just beside their tzitzit, the ritual tassels mandated by Jewish law, as clusters of children play in the streets. Once largely confined to the fringes of Israeli society, an ultranationalist political outlook forged in Jewish West Bank settlements like Kiryat Arba has now been thrust to the center of Israeli public life by Mr. Ben-Gvir’s success in last week’s election. The Religious Zionism ticket co-led by Mr. Ben-Gvir won 14 seats in the 120-seat Parliament, or Knesset, making it the third-largest party in Israel.

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