Is the cross sign found in the emblems of Barcelona and Milan clubs, and the emblem of Brazil (which is not the emblem of the Brazilian Federation), truly a cross sign or a plus sign, and is advice obligatory for whoever wears it?

The cross is a sign of two intersecting pillars that refer to a crucified human. Sheikh Ibn Uthaymeen, may Allah have mercy on him, was asked about the ruling on watches that bear the sign of a cross. He replied that it is obligatory to break a three-dimensional cross, and to efface a cross drawn on watches and the like, and not to carry anything that contains the emblem of the Christians out of veneration for them or imitation of them. He emphasized that the Prophet, peace and blessings of Allah be upon him, used to break and remove crosses, and that a Muslim must keep away from what constitutes the rituals of non-Muslims, due to his saying, peace and blessings of Allah be upon him: "Whoever imitates a people is one of them." As for what is not intended to be a cross, such as the mathematical plus sign, there is no harm in it.

Furthermore, enjoining good and forbidding evil is a communal obligation (fard kifayah), and if some people perform it, the sin is lifted from the rest. The obligation of enjoining good and forbidding evil is not waived from the accountable person merely because he thinks it will not be beneficial.