Take baptism, for example. Like much of early Christian worship, Baptism was a Jewish custom. The people living in the Middle East in the first century were already familiar with the practice. So when the Jews and Greeks saw John the Baptist immersing people in the river, they didn't say to themselves "what is this strange act"? It was something they were already familiar with. An article once posted on the Greek Orthodox Archdiocese website said:
A significant parallel exists between Jewish proselyte baptism (when pagans were converted to Judaism) and early Christian baptism. The contacts between early Christian baptism and proselyte baptism, with the similarities in terminology, interpretation, symbolism, and the rite itself, are especially notable. What is of greatest interest, however, is that the baptism of the early Church followed that of proselyte baptism, in which children and infants were baptized with the convert’s family. This is especially significant when one realizes that the very early Church was made up primarily of converted Jews. -“Infant Baptism” by Jordan Bajis.
Baptism, or “mikveh” in Hebrew, is the ceremonial and purifying washing of an object or person in the presence of witnesses. The object or person becomes sanctified, or purified and set aside for a holy purpose. From Old Testament times onward, this has been applied to new mothers, burnt offerings, personal garments, one's hands before a meal, etc. Even in modern Jewish homes, kitchen utensils are immersed in a mikveh, thus a simple meal is transformed into an act of spiritual significance. We can see examples of this ritual in the following Old Testament passages:
Christian baptism was the continuation of the Jewish mikveh - the sanctification and entrance of the person into the faith community. Churches that baptize babies do so with the belief that those who are baptized (infants and adults) are being set apart for a holy purpose and the process of salvation has begun in their lives.
The Old Testament teaches that males coming into the Covenant should be circumcised. Hebrew men who accepted God’s Covenant were to be circumcised, but what about Hebrew children? Did the law require that they wait until an “age of accountability” so they could decide for themselves? No, the Law taught that Hebrew infants were to be circumcised as a sign of God’s covenant, just like any adult convert. The early Church simply continued with this understanding when baptism became the “circumcision of the New Covenant” for the New Testament Christians (Colossians 2).
Forbidding the baptism of infants (“believer’s baptism”) came about in Europe with the Protestant Reformation. In their zeal to distance themselves from anything resembling Roman Catholicism, the Anabaptist and Mennonite reformers lost sight of the historical meaning behind baptism. Protestant theology was heavily influenced by European political ideals, particularly the new emphasis on individual rights and thus baptism became the “public declaration of one’s personal decision.”
In the Conservative and Orthodox Jewish traditions, men and women still go to the purifying waters every shabbat eve. In the Eastern Orthodox Church, full immersion is required, often done in a large basin, exactly as going to the mikveh. Chrismation and the Eucharist immediately follow. Just as the Jewish mikveh is done in view to partake in the Shabbat meals, baptism/Chrismation culminates in the Eucharistic meal.
We are like the burnt offerings and kitchen utensils in a Jewish home in that we can never fully comprehend our sanctification through the mystery of Baptism, no matter what our age is. Yet, we as Christians are separated for a Holy purpose, and we begin the process of salvation through the mystery of Baptism. We are then able to enter God’s temple as “a royal priesthood, a holy nation.”
Jordan Bajis's article is also careful to point out:
Baptism in and of itself, of course, is not enough. It must be accompanied by genuine faith. No parents should be allowed to baptize their infant if they themselves have not made an expressed commitment to serve Jesus Christ and raise their children in accordance with God’s Word. As adults, we are called to accept the challenge of our baptism and live dedicated lives for Christ. If we do any less, we have rejected Christ and the gift of salvation He has made available to us since our birth.
- by David Schneider with the assistance of Fr. Aleksandr Winogradsky Frenkel