TAYBEH, West Bank — Jack Massis, 51, a grocer here in this last entirely Christian village in the West Bank, speaks matter-of-factly about how two of his teenage sons were beaten with clubs last month.

They had argued with members of a Muslim family that had moved three years ago to the edge of Taybeh, a picturesque village in the hills near Ramallah with a dwindling population of 1,300. Mr. Massis’ sons had used a road that ran along the newcomers’ property, which the newcomers insisted was private. The sons spent the night in the hospital, and five members of the Muslim family spent a few days in jail.

In the year since Hamas came to power, some of the fears of a newly Islamist cast to Palestinian society are being borne out. Christians have begun quietly complaining that local disagreements quickly take on a sectarian flavor. And reports of beatings and property damage by Muslims have grown.

In one of the most serious cases, Palestinian gunmen in September set the Y.M.C.A. building on fire in the West Bank city of Qalqilya, where Hamas members hold all 15 local council seats. Muslim figures in the city had previously accused the Y.M.C.A. of engaging in missionary activity and warned it to close down...