Is one who works in printing stickers with religious symbols for series or movies sinful, and is his salary considered lawful?

If the stickers contain images of symbols of disbelief (kufr) or promote vice, then it is not permissible to print them, and the portion of the salary corresponding to printing the forbidden content is unlawful. However, if the stickers do not contain meanings of disbelief or promote vice, then there is no harm in printing them, and the salary is not unlawful.