Complex sentence: Ge'ez, a Semitic language fallen out of daily use several centuries ago, is the liturgical language of the Ethiopic Orthodox Church, whose liturgy is based on that of the Coptic Church.
Split into simpler sentences: Ge'ez, a Semitic language fallen out of daily use several centuries ago, is the liturgical language of the Ethiopic Orthodox Church. The Church's liturgy is based on that of the Coptic Church.