BANGKOK  An uproar among Muslims in Malaysia over the use of the word Allah by Christians spread over the weekend with the firebombing and vandalizing of several churches, increasing tensions at a time of political turbulence.

Arsonists struck three churches and a convent school early Sunday, and black paint was splashed on another church. This followed the firebombing of four churches on Friday and Saturday. No injuries were reported, and only one church, Metro Tabernacle in the capital, Kuala Lumpur, had extensive damage.

The attacks, unlike anything Malaysia has experienced before, have shaken the country, where many Muslims are angry over a Dec. 31 court ruling that overturned a government ban on the use of the word Allah to denote the Christian God.

Though that usage is common in many countries, where Arabic- and Malay-language Bibles describe Jesus as the “son of Allah,” many Muslims here insist that the word belongs exclusively to them and say that its use by other faiths could confuse Muslim worshipers.