from the article:

In Baghdad's predominantly Christian southeastern neighborhood of Karada, only about a dozen people showed up for morning Mass at the Notre Dame de la Deliverance Church. Plainclothes guards armed with guns stood outside the church.

Inside the church, apprehensive worshippers lit candles as priests gave communions.

Services in other churches in Baghdad also had humble attendance, and hotels and shops in Christian neighborhoods did not hang holiday decorations as they usually do.