In Acts 2, God’s people are celebrating Pentecost (the Festival of Weeks). As part of it, they are remembering God’s provision and how he came in power to Mt. Sinai in Exodus 19-20ff and gave the Law. While all this is going on, God shows up again in a history-changing way. Rather than descend on a place in power, the Holy Spirit descends upon a people in power as the Church begins. When someone becomes a Christian, they are baptized with the Holy Spirit (he indwells them). This happens one time in each believer’s life at the moment of conversion. Additionally, though, Christians are to be filled with the Spirit, empowered by him. Filling happens multiple times as we abide in Christ. God sends his Holy Spirit to empower us with good news that some receive and others reject.