The symbol in these paintings is popularly used in North Africa and the Middle East and mostly associated with the Islam (Hamsa or Hand of Fatima). It is also used in Judaism (Hamesh) and Levintine Christianity. The hamsa actually pre-dates Islam and Christianity and seems to have been in use since around 800BCE.
The hamsa is best known for its protective powers and its ability to avert the evil eye. Many traditions use the open right hand as a symbol of power, protection and blessing. For instance both Buddha and Jesus are depicted with an open raised right hand symbolising freedom from fear through blessings (Christianity) or the power of the teachings (Buddhism).
The crescent moon is a symbol often used along with the hamsa to enhance the power of the symbol to avert the ‘evil eye.’
The crescent moon is derived from ancient goddess religions who regard the moon as having the power of life, probably associated with the moons connection to tides, time and water.
The hand talisman itself may have originated from worshippers of the moon who are depicted in Canaanite art stretching their hands to the moon in prayer and admiration.