Complex sentence: The law is a remnant of the Napoleonic Concordat of 1801, which was abrogated in the rest of France by the law of 1905 on the separation of church and state.
Split into simpler sentences: The law is a remnant of the Napoleonic Concordat of 1801. The 1801 Concordat was abrogated in the rest of France by the law of 1905 on the separation of church and state.