What is the ruling on a Muslim employee wearing a cross on their work uniform if they work in a Christian hospital and it is mandatory?

It was part of the Prophet's guidance (peace and blessings be upon him) to destroy any image of a cross if found, because it is a symbol of a distorted religion that falsely and mendaciously asserts the crucifixion of the Messiah. 'Aisha (may Allah be pleased with her) narrated that the Prophet (peace and blessings be upon him) "would not leave anything in his house that had crosses on it without destroying it."

The Permanent Committee has issued a fatwa (definition) prohibiting prayer in clothes that have a cross on them, and obligating its removal in a way that obliterates its image. A Muslim is not pleased to place on his clothes an idol worshipped besides Allah, which points to a false religion, because Allah Almighty nullified the belief in crucifixion by saying: "And they did not kill him, nor did they crucify him; but [rather] it was made to appear to them so."

Therefore, the Sharia (definition) ruling is prohibition, and Allah Almighty has promised the pious ease and provision.