Complex sentence: Warnke then left Cerullo's ministry to start his own, forbidding Cerullo to use any of his material, and he and Balsiger went on to write the book that would make Warnke famous.
Split into simpler sentences: Warnke then left Cerullo's ministry to start his own, forbidding Cerullo to use any of his material. It was at this time that Warnke and Balsiger went on to write the book that would make Warnke famous.