The first Christian congregations worshipped in private houses, meeting at the homes of wealthier members on a rotating basis. By the second century A.D., there is evidence that some of these houses were donated to the congregations and converted into churches. Such a conversion took place at Dura-Europos in approximately A.D. 240.
Since Christian worship was still proscribed and subject to persecution in the second and third centuries, it was necessary for Christian places of worship to be discreet, if not completely secret. Thus the converted house-church usually, as at Dura-Europos, showed no exterior change. Worship was generally conducted in the atrium, or central courtyard of the house. 
Here the early church at Dura-Europos differs: the meeting hall used for worship and prayer was created by knocking down the wall between two adjacent rooms off the left side of the atrium. Across the atrium, on the right side, another room was transformed into a baptistery that was subsequently richly decorated with Christian paintings.

The Dura-Europos baptistery was a small room with a baptismal font at one end. Baptism was by immersion and the font, located under a columned vault, was large enough to hold a person. As mentioned above, the baptistery was decorated with a cycle of Christian paintings; a painting of Christ as the Good Shepherd, for instance (visible at right), appeared above the font. Clearly Dura-Europos’s Christian congregation, like its Jewish community, did not adhere strictly to the prohibition against images in effect during the early centuries A.D. The remaining three walls seem to have shown subjects from the New Testament: the Samaritan woman at the well, Christ walking on the water, Christ healing the paralytic, and the women visiting Christ’s tomb after the Resurrection. 
Modern scholars continue to debate the iconography of these paintings since the images do not appear to correspond precisely to extant early biblical texts. The paintings also included one Old Testament subject, David and Goliath, and there are traces of a scene suggesting Paradise. A small drawing of Adam and Eve was added to the Good Shepherd painting at some point after its completion.

Baptism and the Eucharist were the two most important sacraments to the early Christian Church. Both were viewed as signs of the salvation promised by Christ to his followers. The subjects chosen for the Dura-Europos baptistery paintings are particularly in sync with the times since the themes represented center on deliverance and salvation. In this respect, the Dura-Europos paintings are comparable to the paintings in the Roman catacombs. They also serve as evidence that precursors for thematic cycles of mosaics showing Christ’s miracles and scenes from the Old Testament existed in the early Church.
The controversy over the use of pictorial decoration in the Church was ultimately resolved in its favor. In the words of Pope Gregory the Great in about A.D. 600, “Pictures are used in the church so that those who are illiterate may by looking at the walls read there what they are unable to read in books.”