A prominent Christian surgeon in the Gaza Strip said assailants threw a bomb at his vehicle and sent him threatening messages.
Dr. Maher Ayyad, 55, says no one was hurt in Friday's bombing, though the explosion damaged his brother's vehicle.
He said Sunday that after the blast, he received text messages to halt evangelical work or face harsh punishment. Ayyad says he does not preach his faith.
There are some 3,000 Christians in Gaza amid a population of some 1.5 million Muslims. They mostly have good relations. But some Gaza Christians have reported harassment by religious hardliners since the terrorist Islamic group Hamas seized power in 2007.
There have been sporadic attacks against Christians.