But you shall receive power when the Holy Spirit has come upon you; and you shall be witnesses to Me in Jerusalem, and in all Judea and Samaria, and to the end of the earth. Acts 1:8
Recommended Reading – Acts 2:1-4, 14
Generally, the theory of causation seeks to explain the connection between one event (the cause) and another (the effect). There are causes and effects throughout life—even in the Christian life.
A clear cause and effect is seen in Acts 2. The effect was that the apostles of Christ suddenly began carrying out Christ’s Great Commission to preach the Gospel and teach and baptize new believers. And the cause? The descent of the Holy Spirit to fill the apostles. Prior to ascending into heaven, Christ connected the spiritual cause with the practical effect: “You shall receive power when the Holy Spirit has come . . . ; and you shall be witnesses to Me” (Acts 1:8). Prior to Pentecost, the disciples had been fearful and intimidated. After Pentecost, they were powerful witnesses. The cause of this transforming effect was the Holy Spirit.
Is it any wonder that Paul admonished the church in Ephesus to be filled with the Holy Spirit (Ephesians 5:18)? Create a clean vessel (1 John 1:9) for the Spirit to fill on a daily basis.
“Witnessing is simply sharing Christ in the power of the Holy Spirit and leaving the results to God.”