Ramadan is tied to the Muslim calendar and therefore every year it passes at different times. But there is nothing to worry about if your trip hits the Ramadan period in Egypt. No special requirements for tourists at this time does not appear. Simply the Egyptians themselves refrain from eating until dark.
By the way, hotels for the Ramadan period should be booked in advance, since a large number of tourists from neighboring Muslim countries traditionally come to Ramadan to Egypt.
Egyptians tolerate representatives of other religions. In the country there are Orthodox shrines, Christian churches. In Egypt, Copts still live in large numbers - Christians. By the way, our Russians who live in Egypt permanently are mostly Christians. And no one requires a change of religion from them.