Gregory Walter Graffin , Ph. D. ( born November 6 , 1964 at Racine , Wisconsin ) , better known to the public as Greg Graffin , is the vocalist and a songwriter of Bad Religion , which he co-founded in 1980 and is the band 's only constant member , even though it now features two of their original members , guitarist Brett Gurewitz ( who left and rejoined the band twice ) and bassist Jay Bentley ( who left in 1982 , but returned in 1986 ) . Gregory Walter Graffin , Ph. D. ( born November 6 , 1964 ) is an American punk rock musician , college professor , and author . He is most recognized as the lead vocalist and songwriter of the noted Los Angeles band Bad Religion , which he co-founded in 1979 and is the band 's only constant member , even though it now features two of their original members , guitarist Brett Gurewitz ( who left and rejoined the band twice ) and bassist Jay Bentley ( who left in 1982 , but returned in 1986 ) .