Just looked up the origin of the Welcome Table. In Jewish tradition "by the Seder table at which one seat is left empty for Elijah or the stranger. Modeled in the Christian tradition by Jesus' radical table fellowship with sinners and prostitutes. Sung in the African-American tradition as the future reign of justice and freedom."

I know little of these roots, so I am probably wrong. Here is the reference:
http://www.firstunitarian.net/publications/sermon/20040208sh.rtf