The Oxford English Dictionary defines altar as a block, pile, table, stand, or other raised structure, with a plain top, on which to place or sacrifice offerings to a deity. The altar can be a place where incense is burned in worship. Nearly all world religions and faiths have use of an altar. The classical Hebrew sense of the altar is as the meeting place between heaven and earth. The physical altar becomes the place of meeting between the Creator and humanity. It is the place of sacrifice and of communion. The altar is always a very special place of devotion and deepest respect. In many religions, the altar began as the place of sacrifice. This altar would have been temporary and erected for the moment. Offerings were made to a deity, including fruits, vegetables, animals, and even humans (in some societies and times). Once a faith tradition or religion became a bit more permanent, the altar was eventually turned into a very permanent structure located inside a sacred building, temple, or church. Only the ritually trained were allowed to come to the altar. Barriers and railings were set up to keep out those not fully trained to minister at the altar. Christianity sees the altar on many levels. The altar is where simple gifts of bread and wine are placed for Eucharistic worship. The altar becomes the table of the Lord. The Last Supper of Jesus sees a meal becoming a time for theology. The altar and/or table now takes on deeper meaning. Just like in any family, a special meal with family gathered takes on a deeper meaning. The table indeed becomes an altar. Great care is taken to set the table/altar, special vessels are used on the table/altar, and stories are shared (sacred scriptures are proclaimed). Once at the table, people tend to stay there. Being allowed at the big persons' table is seen as an initiation into adulthood. The meal is more than just a sharing of food. Even though one may take great pride in a beautifully set table/altar, it is the experience of communion with one another that is of prime importance. After Jesus' resurrection from the dead, it was at table that he revealed himself to his followers, in the breaking of the bread. Again, it is the table/altar that becomes a place of action and of convergence between believers and the deity.
More recently, a split in understanding of the altar has developed. The altar has become a place for meals, remembrance, and community. The older idea of altar as the place of sacrifice is fading away in some circles of believers. The altar is now seen as the table of the Lord where the community gathers. Some communities try to hold on to the multiple ideas of altar.
Some would see the altar as the place of sacrifice, the Lord's Table, and a place of nourishment and strength for the community gathered. The altar can be a table of joy, a place of communion and peace, and a source of unity and friendship.
There is one final aspect of altar that is slowly being forgotten. The altar has also been a place of memorial for a person who died for the faith or the deity. The graves of special people had altars erected on them in some religious faiths. The purpose of this altar was to be a memorial of the martyr's death. In fact, in most Roman Catholic churches, altars have to have a relic (an object of a saint) placed into the altar. Some ancient churches are built over the remains of an early believer (e.g., the central church of Roman Catholicism, the Vatican in Rome, is built on Saint Peter's remains). Today, most communities would see the altar as a place of gathering of the believers. It is a place where the mystery of God's gift unfolds, and the community is nourished and fed. The altar should be seen as a place where all are welcomed, where the poor find justice, victims of oppression find freedom, and the whole of humanity is reunited with its Creator.