Question:
May a Jewish jeweler manufacture, purchase, or sell gold and silver cross necklaces and similar Christian symbols?
Answer:
From a strictly halachic perspective, there is room to distinguish between a cross and an actual object of idolatrous worship.
The cross, as commonly used today, is generally viewed as a symbol of Christianity and not as an object that is itself worshipped. Accordingly, before it reaches the hands of a Christian owner, and certainly before it is ever used in any religious context, it does not automatically assume the status of an object of idolatry whose benefit is forbidden. For this reason, some Poskim argue that the severe laws prohibiting benefit from idolatrous objects do not necessarily apply to the manufacture and sale of ordinary cross jewelry. This especially applies if gentile workers are the ones doing the manufacturing of the cross necklace on behalf of the Jewish jewelers.
Nonetheless, even the above Poskim strongly discouraged engaging in such a trade. Even if one cannot classify the item as actual idolatry, it remains a prominent religious symbol of another faith. It is therefore considered highly inappropriate for a Jew to involve himself in producing, marketing, and distributing articles that promote or represent Christian worship and belief.
Accordingly, while there may not be a clear-cut prohibition of benefiting from idolatry in the sale of ordinary crosses, many Poskim viewed the practice negatively and considered it unbecoming for a Jew to engage in the manufacture and sale of such items. A G-d-fearing person should distance himself from involvement in the production and sale of religious symbols of other faiths whenever possible.
Sources:
See Admur O.C. 113:7; Michaber O.C. 113:8; Rama Y.D. 141:1; Shach 141:3, 4, 6; Ravayah; Mordechai; Batei Kehuna 1:13; Zera Emes 45; Maharam Shick 152; Chochmas Adam 85; Arugas Habosem Y.D. 129; Minchas Elazar 1:53; Darkei Teshuvah 141 in name of Shut Nehar Afarsamon that selling the cross is Mutar and manufacturing through gentile is Mutar; Igros Moshe O.C. 1:69; Shulchan Menachem 4 p. 36; Ohel Yaakov 141:16; Divrei Yatziv Y.D. 45; Kovetz Teshuvos 3:120; Yisa Yosef Y.D. 26; Chayeh Halevi 7:39-4; Halichos Chinuch p. 117; Ashrei Haish Y.D. 10:1; Piskeiy Teshuvos 154:30