Complex sentence: Torquemada's concern about Spanish Jews grew as he perceived them to be gaining increasing religious influence on, and economic domination of, Spain; he became convinced they were trying to undermine the sovereign couple's power and, even more importantly, Roman Catholicism.
Split into simpler sentences: Torquemada's concern about Spanish Jews grew as he perceived them to be gaining increasing religious influence on, and economic domination of, Spain. He became convinced they were trying to undermine the sovereign couple's power and, even more importantly, Roman Catholicism.