In his Bull of 1302 , Unam Sanctam , Boniface VIII proclaimed that it `` is absolutely necessary for salvation that every human creature be subject to the Roman pontiff '' , so he pushed papal supremacy to its historical extreme . In his Bull of 1302 , Unam Sanctam , Boniface VIII proclaimed that it `` is absolutely necessary for salvation that every human creature be subject to the Roman pontiff '' , pushing papal supremacy to its historical extreme .