On Idolatry by Tertullian
Chapter XXII.--Of Accepting Blessing in the Name of Idols.
Equally, one who has been initiated into Christ will not endure to be blessed in the name of the gods of the nations, so as not always to reject the unclean benediction, and to cleanse it out for himself by converting it Godward. To be blessed in the name of the gods of the nations is to be cursed in the name of God. If I have given an alms, or shown any other kindness, and the recipient pray that his gods, or the Genius of the colony, may be propitious to me, my oblation or act will immediately be an honour to idols, in whose name he returns me the favour of blessing. But why should he not know that I have done it for God's sake; that God may rather be glorified, and demons may not be honoured in that which I have done for the sake of God? If God sees that I have done it for His sake, He equally sees that I have been unwilling to show that I did it for His sake, and have in a manner made His precept a sacrifice to idols. Many say, |No one ought to divulge himself;| but I think neither ought he to deny himself. For whoever dissembles in any cause whatever, by being held as a heathen, does deny; and, of course, all denial is idolatry, just as all idolatry is denial, whether in deeds or in words.