OLDWICK, N.J.–(BUSINESS WIRE)–A.M. Best has downgraded the Financial Strength Rating (FSR) to A- (Excellent) from A (Excellent) and the Long-Term Issuer Credit Ratings (Long-Term ICR) to “a-” from “a” of GuideOne Mutual Insurance Company (West Des Moines, IA) and its wholly owned subsidiaries: GuideOne Specialty Mutual Insurance Company, GuideOne America Insurance Company, GuideOne Elite Insurance Company, GuideOne National Insurance Company, and GuideOne Property & Casualty Insurance Com