XVIII. May a Christian buy and use vegetables or fruit which he knows to have been brought from the garden of a temple or of the priests of an idol? That you may not be put to trouble in searching the Scriptures concerning the oath of which I have spoken and the idols, I resolved to set before you those texts which, by the Lord's help, I have found; but if you have found anything better or more to the purpose in Scripture, be so good as let me know. For example, when Laban said to Jacob, “The God of Abraham and the God of Nahor judge between us,” Scripture does not declare which god is meant. Again, when Abimelech came to Isaac, and he and those who were with him swore to Isaac, we are not told what kind of oath it was. As to the idols, Gideon was commanded by the Lord to make a whole burnt-offering of the bullock which he killed. And in the book of Joshua the son of Nun, it is said of Jericho that all the silver, and gold, and brass should be brought into the treasures of the Lord, and the things found in the accursed city were called sacred. Also we read in Deuteronomy: “Neither shall you bring an abomination into your house, lest you be a cursed thing like it.”
May the Lord preserve you. I salute you. Pray for me.
Source: Letters (New Advent)