What are the forms of the cross, and are the plus sign and the multiplication sign considered among its forms?

The manufacturing, purchase, or engraving of a cross is prohibited (haram (definition)). It is impermissible for a Muslim to commit such an act or to assist in it, because it is a symbol of disbelief (kufr). As Ibn Taymiyyah mentioned, selling and making it is prohibited, just like idols.

The cross has many shapes and types: 1. If it is drawn as a cross: It is forbidden to carry it, wear it, buy it, sell it, or draw it, because the reason for the prohibition is to avoid imitating Christians and glorifying their false symbols. This applies to any form of the cross if its intent is glorification and symbolism. 2. If the shape of the cross results from ornamentation or ordinary, unintentional things: a. If it is apparent to the viewer at first glance that it is the well-known cross: It must be removed or altered so that it ceases to be a cross, because the Prophet (peace be upon him) "would not leave anything in his house that had crosses on it without breaking them." b. If the image of the cross is not apparent, or if it results from unintentional ornamentation or the use of mathematical symbols: There is no harm in it, due to the absence of the reason for imitating disbelievers and glorifying their symbols.

Ibn Uthaymeen affirmed that the prohibition includes cases where it is known to be a cross and is placed as a cross, not merely an engraving. He also stated that the prescribed cross consists of two lines, one vertical and the other horizontal, such that the vertical line is longer than one of its sides. As for things not intended as a cross, such as the plus sign or some geometric symbols, there is no harm in them.