"As the lightning cometh out of the east and shineth even unto the west, so shall also the coming of the Son of Man Be." Matt. 24:27
Based on this passage the dogma of Christ's second coming arriving from the east developed, hence the altar being at the east end of the Church so the congregation and priest will be facing the Lord on the last day.
A little known bit of History: The masons who built the cathedrals had somewhat "secret knowledge" about the movement of the planets in relation to the sun. When a new Church was being lined off on the ground they were called in to orient the Church properly.
If the Church was being dedicated to St. Lorentz for instance, it would be oriented so that on the feast day of St. Lorentz, the sun would rise and shine in the chancel window directly over the altar.
A little more trivia... Again, based on this passage, many cemeteries are laid out so that the dead are buried with their feet to the east, with the idea that when the dead rise on the last day they will face the Lord. Less than a Century ago, one who took their own life would be buried the other way around so that on the day of judgment they would rise with their back turned to the Lord, the way it was believed that they did in life.
The Lutheran Church where I grew up had its Chancel facing North. The Church was oriented to the road, but our three cemeteries all faced east!