On Idolatry by Tertullian
Chapter II.--Idolatry in Its More Limited Sense. Its Copiousness.
But let the universal names of crimes withdraw to the specialities of their own works; let idolatry remain in that which it is itself. Sufficient to itself is a name so inimical to God, a substance of crime so copious, which reaches forth so many branches, diffuses so many veins, that from this name, for the greatest part, is drawn the material of all the modes in which the expansiveness of idolatry has to be foreguarded against by us, since in manifold wise it subverts the servants of God; and this not only when unperceived, but also when cloaked over. Most men simply regard idolatry as to be interpreted in these senses alone, viz.: if one burn incense, or immolate a victim, or give a sacrificial banquet, or be bound to some sacred functions or priesthoods; just as if one were to regard adultery as to be accounted in kisses, and in embraces, and in actual fleshly contact; or murder as to be reckoned only in the shedding forth of blood, and in the actual taking away of life. But how far wider an extent the Lord assigns to those crimes we are sure: when He defines adultery to consist even in concupiscence, |if one shall have cast an eye lustfully on,| and stirred his soul with immodest commotion; when He judges murder to consist even in a word of curse or of reproach, and in every impulse of anger, and in the neglect of charity toward a brother just as John teaches, that he who hates his brother is a murderer. Else, both the devil's ingenuity in malice, and God the Lord's in the Discipline by which He fortifies us against the devil's depths, would have but limited scope, if we were judged only in such faults as even the heathen nations have decreed punishable. How will our |righteousness abound above that of the Scribes and Pharisees,| as the Lord has prescribed, unless we shall have seen through the abundance of that adversary quality, that is, of unrighteousness? But if the head of unrighteousness is idolatry, the first point is, that we be fore-fortified against the abundance of idolatry, while we recognise it not only in its palpable manifestations.