Dogmatic Sarcophagus [SEP] collection
Dogmatic Sarcophagus
The Dogmatic Sarcophagus, also known as the "Trinity Sarcophagus" is an early Christian sarcophagus dating to 320–350, now in the Vatican Museums (Vatican 104). It was discovered in the 19th century during rebuilding works at the basilica di San Paolo fuori le Mura, in Rome, Italy.
Together with the Sarcophagus of Junius Bassus, it one of the most important examples of Christian-Roman sculpture of the Constantinian era. It draws its name from its clear references to the dogmas of the Council of
to the single figure of God, in Christian terms, God the Father. However the first person plural in Genesis 1:26 "And God said, Let us make man in our image, after our likeness", and New Testament references to Christ as creator (John 1:3, Colossians 1:15) led Early Christian writers to associate the Creation with the Logos, or pre-existing Christ. 
A number of other sarcophagi, most conveniently collected in the same Vatican collection as the Dogmatic Sarcophagus, also show groups of three figures