Final answer:
The Holy Spirit arrived at the church on Pentecost, fifty days after Easter, marking a pivotal moment in Christian history as the Apostles began to spread the Gospel. This event represents the empowerment of the church's mission and the establishment of the belief in the Holy Trinity.
Step-by-step explanation:
The Descent of the Holy Spirit
The Holy Spirit came to the church on the day of Pentecost, which is the fiftieth day after Easter (also known as Pascha). This event is described in the biblical book of Acts, chapter 2, and marks the fulfillment of Jesus' promise to send the Advocate (Holy Spirit) to His Apostles. The descent of the Holy Spirit occurred in the form of tongues of fire and inspired the Apostles to preach the message of the crucified and risen Christ in various languages, allowing people of different tongues to understand. This miraculous event facilitated the spread of Christianity and is often considered the birth of the Christian church.
In the history of the early Christian church, this moment is critical as it represents the beginning of the church's mission to spread the Gospel to all nations. The concept of the Holy Trinity—God the Father, God the Son, and God the Holy Spirit—was solidified in orthodoxy during the second and third centuries. The Holy Spirit is viewed as the presence of God that empowers believers and the church, which has continued to influence the lives of Christians, guiding them in their faith.