Heresy was a capital offense against the secular law of most European countries of the 13th century. Kings and emperors, even those at war with the papacy, listed heresy first among the crimes against the state. Kings claimed power from God according to the Christian faith. Often enough, especially in that age of papal claims to universal worldly power, the rulers' power was tangibly and visibly legitimated directly through coronation by the pope.
Simple theft, forgery, fraud, and other such crimes were also capital offenses; Thomas's point seems to be that the gravity of this offense, which touches not only the material goods but also the spiritual goods of others, is at least the same as forgery. Thomas's suggestion specifically demands that heretics be handed to a "secular tribunal" rather than magisterial authority. That Thomas specifically says that heretics "deserve ... death" is related to his theology, according to which all sinners have no intrinsic right to life ("For the wages of sin is death; but the free gift of God is eternal life in Christ Jesus our Lord"). Although the life of a heretic who repents should be spared, the former heretic should be executed if he relapses into heresy. Thomas elaborates on his opinion regarding heresy in the next article, when he says: