An elder was the title used in the Jewish community and is rarely used in the Christian community today, but can be. It refers to a person who is a spiritual advisor due to his or her age. A bishop is an overseer who supervises several churches. The pastor or minister is the spiritual overseer or spiritual leader of his church. A pastor or minister will only serve one church at a time and will lead that church in their weekly services as well as extracurricular church programs. Sometimes, the pastor or minister will be addressed as a reverend. The exact title used for the position varies from church to church and denomination to denomination.
The title of pastor actually came to be because the word itself means "shepherd." This is a metaphor that is seen in the Bible when it is said that God leads a flock of sheep, which are his Christian followers. The term "pastor" is used similarly here as it means that the pastor is shepherding his flock of churchgoers towards Christ and eternal salvation.
Christmas Eve
Christmas Eve has many of its own customs and traditions. The most widely practised one that still exists today is going to a Midnight Mass Church Service. In many countries, especially Catholic ones such as Spain, Mexico, Poland and Italy, this is the most important Church service of the Christmas season. People might fast during Christmas Eve (not eat any meat or fish usually) and then the main Christmas meal is often eaten after the Midnight Mass Service in these countries. In some other countries, such as Belgium, Finland, Lithuania and Denmark the meal is eaten in the evening and you might go to a Midnight Service afterwards! The Midnight Mass Communion Service (or 'Christ-Mas') was a very special one as it was the only one that was allowed to start after sunset (and before sunrise the next day), so it was held at Midnight! (Source: www.whychristmas.com/)