The Tradition in Judaism
There is a common belief that Jews pray to the east. There is nothing that says this is so. What Jews are asked to do is to face the direction of where the temple once stood in Jerusalem. This temple was destroyed by the Romans in AD70 following the Jewish rebellion.
After that period, the Jews were scattered around Europe. The geographical location meant that when they prayed towards the temple, they had to face the east. This is where the idea of facing the east in prayer probably originated.
But for those living in Turkey and near it, they must look west to face the temple. So while it is true that a lot of Jews in Europe orient their prayers to the east, it has nothing to do with the prayer itself.
The Tradition in Islam
Muslim prayer is oriented this way so they are facing Mecca. Mecca in Saudi Arabia is the holiest land for Muslims. In 622 the Prophet Mohammed was forced to leave Mecca due to persecution from his enemies. In the ensuing years however, Islam spread rapidly. In 630, Mohammed was able to return to Mecca triumphantly.
Today, Muslims are asked to make a pilgrimage to the city if they can. If not, they should worship oriented towards it. That is where the tradition of facing the east in prayer originated among Muslims. To this day this is still being observed by all devout followers of Islam.
The Tradition in Christianity
There are still some sects which celebrate their mass facing this direction. The reason why this direction was chosen is unclear. It could have simply been adopted from the Jewish practice. It is also possible that the early Christians believed that the rising sun in a way symbolized the resurrection and hope in Christ.
The Church itself is unclear on how this practice started. In fact there are those who argue that this is not necessary at all. They point out that since God is present everywhere, it does not make a difference which direction you are praying. Still, the notion of facing the east in prayer has remained in the minds of people.
However, some traditionalists still maintain that the orientation is crucial. Some Christians and theologians believe that the east is very symbolic. It represents the Son of Man. It has come to signify the cross and the Second Coming as well.
Adherents of the Eastern Church also pray in the direction of the rising sun. Their edifices are also oriented as such. There belief is based on Biblical passages including 1 John 1:5 and Mal 3:20.
These passages signify that Christ is equivalent in some way to the Sun. The Garden of Eden was created in the east too. By praying in that direction, man expresses a desire to return to God.
The reasons for facing the east in prayer are numerous. While some may believe that it is no longer relevant, others continue to adhere to it and it’s unlikely to change.