Baetyl (or Baitylos, Beth-El): a venerated stone, believed to be in some sense the "house of god".
It is not entirely clear whether the baetyls themselves were the object of worship, or that they were symbols (or guarantees) of the divine presence. Probably there was confusion, just like Christians disagree whether the bread they share is Christ, guarantees the covenant with Christ, or symbolizes Christ.
The Bible mentions a town called Bethel; an echo of the old belief can be found in Psalm 28.1, where God is likened to to a rock, and at a later stage, the prophets of Israel and Judah polemized against the worshippers of these stones. In our own age, Muslims worship God in the Kaaba in Mecca, which contains a famous black stone that was already a cult object before the ministry of the prophet Muhammad.The belief in baetyls was also known in the world of the Greeks, who venerated these stones in Paphos ("the needle of Aphrodite"), Ephesus (Artemis), and Delphi.(Apollo). However, in the classical age, the Greeks no longer remembered the origin of this cult. To explain its significance, they said that once, in the mythological past, the supreme god Zeus had released two eagles at the edges of the earth, which had met each other above the sacred city. A monument was erected to celebrate the outcome of this mytho-scientific experiment: it was called the omphalos ('navel').
It is interesting to see that in the early third century, the Roman emperor Septimius Severus (193-211) built an umbiculus ('navel') in Rome. He may have been thinking about the Greek example, but it is also remarkable that Severus' wife Julia Domna was the daughter of the high priest of Elabal in Emesa.
It has been suggested that the Christian cult of Saint Simeon the Stylite (c.390-459), who used to live on a tall pillar that was after his death venerated by the Arabs, was an attempt to convert them to Christianity by offering them a stone to worship.