For any Christians visiting Qatar, that would like to attend a church service. You can pop along to the Religious Complex located in Abu Hamour. Taxi drivers will know how to get you there no problem. But here is a map just in case.
You need to be aware that the religious day in the Gulf Region is on a Friday not a Sunday. Although most churches offer a Sunday evening service, Friday is the day most people are not in work. And thus the main services are on a Friday.
For more information please click on one of the links below
The Church of the Epiphany (Anglican)
Our Lady of the Rosary (Catholic)