Business of Insurance Regulatory Reform Act of 2018 This bill amends the Consumer Financial Protection Act of 2010 to revise the authority of the Consumer Financial Protection Bureau (CFPB) over activities regulated by a state insurance regulator. The CFPB may not enforce the Act against any person regulated by a state insurance regulator and offering a consumer financial product or service, to the extent that person is engaged in the business of insurance. If a person engaged in the business of insurance is regulated by a state insurance regulator but otherwise subject to the Act, the CFPB must construe its authority narrowly.