Complex sentence: While popularized by Reagan, "The Eleventh Commandment" was created by then California Republican Party Chairman Gaylord Parkinson to help prevent a repeat of the liberal Republican assault on Barry Goldwater that contributed to Goldwater's defeat in the 1964 presidential election.
Split into simpler sentences: While popularized by Reagan, "The Eleventh Commandment" was created by then California Republican Party Chairman Gaylord Parkinson. The goal was to prevent a repeat of the liberal Republican assault on Barry Goldwater, attacks which contributed to Goldwater's defeat in the 1964 presidential election.