Complex sentence: Most Egyptian deities were first worshipped by very local cults, and they retained those local centres of worship even as their popularity spread, so that most major cities and towns in Egypt were known as the home of a particular deity.
Split into simpler sentences: Most Egyptian deities were first worshiped by small local cults, and they retained those local centres of worship even as their popularity spread. Most major cities and towns in Egypt were known as the home, or center of worship, for a particular deity.