Republican officials and candidates in Texas have shifted their rhetorical attack lines from the border fears that dominated recent elections to the state’s growing Muslim population, with language that echoes the aftermath of the terror attacks of Sept. 11, 2001. The rise of anti-Muslim rhetoric has unnerved many in the state’s Islamic community while sending signals to Republicans outside Texas who might be searching for rhetorical targets now that the nation’s southwestern border has grown quiet. Ads for Senator John Cornyn of Texas have touted his fight against “radical Islam.” Texas Republican lawmakers created a “Sharia-Free America Caucus” in Congress....