The "First Day of the Week" holds significant importance in Christian theology and practice, primarily recognized as Sunday in the modern calendar. This day is notably associated with the resurrection of Jesus Christ, which is a cornerstone event in Christian faith.

Biblical References:

1. Resurrection of Jesus Christ: The most pivotal event associated with the first day of the week is the resurrection of Jesus. According to the Gospel accounts, Jesus rose from the dead on this day. In the Berean Standard Bible, Matthew 28:1 states, "After the Sabbath, at dawn on the first day of the week, Mary Magdalene and the other Mary went to see the tomb." Similarly, Mark 16:2 records, "Very early on the first day of the week, just after sunrise, they went to the tomb."

2. Appearances of the Risen Christ: The first day of the week is also marked by several post-resurrection appearances of Jesus to His disciples. In John 20:19 , it is written, "It was the first day of the week, and that very evening, while the disciples were together with the doors locked for fear of the Jews, Jesus came and stood among them. 'Peace be with you!' He said to them."

3. The Early Church Gatherings: The early Christian community began to gather on the first day of the week for worship and breaking of bread, signifying the importance of this day. Acts 20:7 notes, "On the first day of the week, we came together to break bread. Paul spoke to the people and, because he intended to leave the next day, kept on talking until midnight."

4. Collection for the Saints: The Apostle Paul instructed the Corinthian church to set aside a collection for the saints on the first day of the week, indicating its significance for communal activities. In 1 Corinthians 16:2 , Paul writes, "On the first day of every week, each of you should set aside a portion of his income, saving it up, so that when I come no collections will be needed."

Theological Significance:

The first day of the week, Sunday, became known as the Lord's Day, a term that reflects its association with the resurrection of Christ. This day is seen as a celebration of the new creation inaugurated by Jesus' victory over death. The shift from the Jewish Sabbath (Saturday) to Sunday worship underscores the new covenant and the fulfillment of the Old Testament promises through Christ.

Historical Context:

In the early Christian era, the first day of the week gradually became the primary day of worship and rest for Christians, distinguishing them from Jewish customs. This transition was solidified over the centuries, particularly after the Edict of Milan in 313 AD, which granted religious freedom within the Roman Empire and allowed Christians to worship openly.

Cultural and Liturgical Practices:

Today, Sunday is widely observed by Christians around the world as a day of worship, rest, and reflection. It is a time for communal gathering, prayer, and the celebration of the Eucharist or Communion, commemorating the resurrection of Jesus and His ongoing presence in the life of the Church.

The first day of the week continues to be a symbol of hope, renewal, and the eternal life promised through Jesus Christ, serving as a weekly reminder of the transformative power of His resurrection.